Integrated rail and track condition monitoring system with imaging and internal sensors

ABSTRACT

A railroad track inspection system has multiple track scanning sensors, a data store, and a scan data processor. The scan data processor provides automatic analysis of the track scan data to detect track components within the scan data from a predetermined list of component types according to features identified in said scan data. The track scanning sensors, data store and scan data processor are attached to a common support structure for mounting the system to a railway vehicle in use. An inertia sensor and common master clock are used to make corrections to the output of the track scanning sensors to accommodate dynamic forces in use. The inspection system may be provided in a single housing for mounting to a conventional passenger/freight rail vehicles and may operate automatically in an unattended mode. The location of track components and/or defects may be logged.

CLAIM OF PRIORITY

This application is a continuation-in-part of the U.S. patentapplication Ser. No. 14/982,312 filed on Dec. 29, 2015, which claimspriority to and the benefit of GB Application No. 1518599.4, filed onOct. 20, 2015, and the disclosure of each of the applications above isincorporated herein by reference in its entirety.

BACKGROUND 1. Field of the Invention

The present invention relates to apparatus for the surveying of railroadtrack, and more particularly, although not exclusively, apparatus forassessing track health based on inspection.

2. Description of Related Art

Railroad tracks, also known as ‘permanent way’, consist of rails,fasteners, sleepers (ties), ballast and the underlying subgrade. A widevariety of variations are possible in terms of types of rail used,jointed or continuous welded, use of sleepers with ballast or slabtrack, type of fastenings used, and switch layouts. A number ofassociated track assets are also mounted on conventional railroad, suchas equipment of signalling, lubrication, cabling and/or switchoperation, amongst others. Over time, track components and assetsdegrade and endure damage because of the physical stress caused bymovement of trains, changes in weather conditions causing compression orexpansion in materials, rain and environmental conditions, anddegradation in material strength with age.

Railroad track inspection processes are aimed at finding missing anddefective components so as to be able to carry out effective maintenancewith the intent of repair or replacement. If the track and associatedassets are not monitored effectively, then there is a risk of completefailure or degradation to the extent that a significant risk is posed tosafe operation of the railroad.

Human track inspectors have conventionally carried out the job of visualtrack inspection by walking along the railway track and taking notes ontrack condition which is later used to guide track maintenanceactivities. Such form of inspection is costly, unsafe, slow and prone tohuman error. Growth in rail networks, coupled with the time required formanual inspection has made it difficult in practice to carry out manualtrack inspection at the required inspection frequency with full networkcoverage.

Over the last two decades, rail infrastructure operators haveincreasingly started to carry out track monitoring using dedicated“inspection trains”. These trains are designed for hosting equipment forsemi or fully automated track inspection equipment. Currently availablesystems of this kind use scanning equipment, including cameras and/orlaser scanners, for monitoring various parts of the track.Implementation of the systems on inspection trains results in thevarious system components being distributed over a local network for thesystem, with sensing equipment being typically mounted on the vehicleexterior and data storage and control systems being mounted with a cabininterior, e.g. within suitable racks.

The implementation and maintenance of such systems is costly, and timeconsuming. In particular, such systems need extensive configuration tofit to a given vehicle which increases the complexity of installationand future maintenance burden. Each inspection train thus requirescustomization such that it is fit for purpose. The overall distributedarchitecture comprising hardware components both outside and inside thevehicle, high power consumption, and the permanent equipment fixturesarrangement means that inspection trains have developed with time astheir own subtype of railway vehicle.

However the cost of running inspection trains is burdensome. Not onlydue to the aforementioned installation and maintenance costs, but alsobecause of the need to schedule inspection train journeys along busyrailway lines. The running of inspection trains is to the potentialdetriment of the railway line capacity for passenger or freightvehicles, particularly considering the relatively low speeds at whichconventional inspection trains gather data.

The data produced by the track scanning process may be transferred to anoff-site computer network, where it can be analyzed. The requirement fordata to be amassed and communicated to a central location forprocessing, coupled with the detailed processing of the recorded data,can lead to a significant delay between the inspection itself and thededuction of any action required based on the inspection. Furthermore itcan be problematic handling the large volumes of scan data generated.

It is an object of the present invention to provide a railroad tracksurveying system that overcomes or substantially mitigates one or moreof the above disadvantages associated with the prior art. It may beconsidered an additional or alternative aim of the invention to providea system that can provide useful track inspection results in a moreconvenient manner.

Although great strides have been made, considerable shortcomings remain.

SUMMARY OF THE INVENTION

According to an aspect of the invention there is provided a railroadtrack inspection system comprising: a plurality of track scanningsensors, a location determining system and an inertia sensor, a datastore for storing track scan data recorded by the track scanningsensors, and a scan data processor for automatic analysis of said trackscan data upon receipt thereof to detect one or more track componentswithin the scan data, wherein the system comprises a common support towhich the track scanning sensors, the inertia sensor, the data store andscan data processor are attached, the common support having a mountingfor attachment of the system to the exterior of a railway vehicle inuse.

The common support may allow attachment of the system to a railroadvehicle as a unit, e.g. as a single fixture or assembly. The commonsupport may comprise a housing, e.g. a rigid enclosure for the internalsystem elements, such that the system can be mounted to the railroadvehicle in the form of an enclosed module. The system may be fitted tonew railway vehicle or retrofitted to existing vehicles in a simplemanner, for example allowing the system to be used on passenger orfreight vehicles, as well as inspection trains and other vehicle types.A single customized support/housing structure allows the internal systemto be optimized for scan data processing such that track analysis can beperformed in, or close to, real time. The system may be portable and maybe transferred from one vehicle to another vehicle by makingmodifications only to the exterior of the host vehicle.

The common support and/or housing may comprise a power and/or dataconnector for the system, i.e. to allow electrical power supply to thesystem and/or data communication between the system and the railroadvehicle and/or another network. A common power and/or data connector forthe whole system may be provided. The system may comprise a datatransmitter and/or receiver.

The scanning sensors may comprise one or more image capture sensor. Theimage capture sensor may comprise a light sensor, e.g. for capturing avisual image, such as a camera. One or more line scan sensor or areascan sensor may be used. Additionally, or alternatively, the scanningsensors may comprise either or both of a laser scanner orthermal/infra-red image capture sensor.

The common support may allow the inertial sensors to be mountedalongside the imaging sensors on a common rigid frame so that inertialsensors experience the same vibration, shock and/or acceleration forcesas imaging sensors, e.g. making such data highly accurate for adjusting,analyzing and/or correcting imaging sensor measurements.

The inertial and imaging sensors operating synchronously for making railtrack measurements including rail profiling, track geometry and visualcondition of track components.

The system may comprise an active source for transmitting energy, e.g.in the visible, x-ray or terahertz spectrum, on or through the track,e.g. comprising one or more track object of interest. The track objectcan be imaged by an appropriate imaging sensor as the residual energyreflects off or transmits through the object which is detected by asensor and converted into an image. The images may show the internalstructure of the object of interest.

The rigid enclosure may comprise a wall structure shaped so as to definea first portion arranged to be located above a rail of the railroadtrack in use and at least one further portion adjacent the firstportion, the first portion facing the rail in use and being recessedwith respect to the further portion.

The common support and/or housing may comprise one or more windowarranged in the field of view between one or more sensor and the trackto be scanned in use. A plurality of window portions may be provided andmay be arranged at different angular orientations, e.g. wherein at leastone window portion is arranged at a different angular orientation to atleast one further window portion. A plurality of window portions may bearranged at opposing angular, e.g. oblique, orientations. A centralwindow portion may be arranged between the opposing window portions. Theopposing window portions may be symmetrical about a central axis orplane, e.g. corresponding to the central axis of a rail in use.

The scan data processor may detect one or more track components withinthe scan data from a predetermined list of component types according toone or more features identified in said scan data. The scan dataprocessor may determine the condition of said one or more trackcomponent.

The scan data processor and/or data store may be provided as a removableprocessing unit or module, which may be releasably coupled, e.g.mechanically and electrically, to the common support and/or housing foruse. The removable processing unit may comprise an enclosure in whichthe scan processor and/or data store is housed. The enclosure maycomprise a data and/or power connector for connection with acorresponding connector on the common support. The removable processingunit may comprise a battery and/or transmitter/receiver circuitry.

The scan data processor may construct, e.g. automatically, an image of alength or section of track from a plurality of scans from one or more ofthe scanning sensors. The scan processor may concatenate a plurality ofimages from a single sensor (e.g. using consecutive scans) or aplurality of sensors.

The scan data may comprise digital image data, for example comprisingpixel intensity values. The scan data may comprise a matrix of pixeldata. The scan data may comprise a visual image and/or thermal image.

The scan data processor may identify pixel clusters within an imageaccording to one or more pixel property, such as brightness or color.Pixel clusters may be used to determine edge, color, texture, shapeand/or other statistical properties for an asset. A pixel cluster mayrepresent an object, such as a track component or part thereof.

The one or more scan data feature may comprise a geometric and/or colorfeature. One or more shape/geometric feature of the track, or acomponent thereof, such as an edge or dimension, may be determined fromone or more image capture sensor, e.g. according to color and/orbrightness/intensity within the captured data. Additionally oralternatively a geometric feature may be determined from a differentscanning sensor such as a laser/distance sensor. A profile of a trackcomponent may be determined using a laser sensor, e.g. a profile of arail.

The plurality of scanning sensors may comprise a plurality of the sameor different types of image capture sensor. Different sensor types maycomprise sensors for different electromagnetic radiationtypes/wavelengths. Alternatively different scanning sensor types maycomprise different sensor dimensionality or orientation, e.g. such asarea scan, line scan, depth detection sensors, three-dimensional surfacescanning/imaging and/or sensors that use active energy transmissionthrough an object to image its internal features (e.g. in the x-ray andterahertz spectrum).

Automatic track component classification and or status assessment may bebeneficially improved by multiple track view analysis. The system maycompare/contrast two-dimensional and three-dimensional scan data of oneor more common track component in determining the component type and/orstatus.

Surface profiling and depth measurement sensors such as lasers may beaccompanied by inertial data measurement sensors to determine trackproperties such as its geometry through the measurement of railsuperelevation, twist, track curvature, and gauge parameters. Inaddition, the depth measurement data may be used to measure rail wear onboth top and side portions of the rail.

Different sensor types may be used in parallel. For example, the outputof each sensor may be used to detect/assess track componentsindependently, e.g. using the same or a different type of assessmentdepending on sensor type. The scan data processor may receive thedifferent sensor inputs and may use them in combination to determine atrack component type and/or track component status. The combination ofdifferent modalities in this manner can provide greater certainty ofautomated track inspection, for example in which a finding using onemodality is compared to a corresponding finding using another modalityin order to confirm or reject that finding.

A common clock may be provided, e.g. for the scan data processor, forlogging and/or processing the sensor signals from the different sensortypes. A common clock signal may be distributed to any combination, orall, of the sensors such that data signals received and logged acrossmultiple sensors (imaging and inertial) is time referenced by the sameclock, e.g. indexed by time. The clock signal must exceed the scanningrate such that each scan receives a unique clock signal. The use of amaster clock for indexing all time references on various sensor outputsignals allows common processing and/or adjustment, assessment and/orcorrection of the imaging sensor data to improve the operation/accuracyof the overall system.

The system may comprise a plurality of track scanning sensors for eachrail under inspection. First and second sensors may or may not bepositioned on either side of the rail, e.g. as flanking sensors. Atleast one sensor may be positioned, e.g. orthogonally or vertically,above each rail so as to provide a plan view of the rail head. At leastone sensor may be laterally offset from the axis, e.g. on either side ofthe rail or a vertical axis/plane of the rail. Any laterally offsetsensor is typically obliquely angled, e.g. relative to an axis/plane ofthe rail.

The system may comprise first and second sets of sensors, each set ofsensors being arranged to scan a single rail, wherein the common supportcomprises a common spacer or lateral support member to which each set ofsensors is mounted, e.g. in a spaced arrangement and/or towards opposingends of the common spacer. The common support may comprise a pluralityof lateral beams.

Any or any combination of the track scanning sensor(s) may be adjustablymounted to the common support, e.g. to adjust the field of view of theimage capture sensor(s). The sensor mountings may be individually orcommonly adjustable. Lateral movement of any or any combination of thescanning sensors may be accommodated. Additionally or alternativelyangular adjustment and/or focal length adjustment may be used.Additionally or alternatively adjustment of a lens and/or aperture maybe used to adjust (e.g. widen/reduce) the sensor field of view. Anangular or focal adjustment mechanism may be provided for each sensor orsensor type, e.g. individually, whereas a lateral movement mechanism maybe provided collectively for the system or the plurality of sensors as awhole.

The track scanning sensors may comprise at least two track scanningsensors mounted at spaced positions relative to the common supportstructure and opposingly oriented so as to scan a common railroad trackcomponent from opposing sides in use.

The common support may comprise an adjustable support structure, e.g. toallow adjustment of the position of the plurality of sensors and/or thesystem as a whole. The common support may allow position adjustmentrelative to the mounting. The common support may comprise a moveableportion, such as a moveable housing/enclosure, which is variablypositionable relative to the mounting. The common support may allowcommon position adjustment for any combination or all of the pluralityof scan sensors, e.g. to accommodate track curvature or the like.

Common position adjustment for the scanning sensors in use may belimited to a single degree of freedom, e.g. lateral adjustment relativeto the direction of the rail(s) under inspection, e.g. such that thesensors remain in the same relative position with respect to the railirrespective of the vehicle speed and track curvature. Common positionadjustment may be used to follow, i.e. dynamically, the direction of therailway track in use, e.g. by remaining aligned with one or both rail ofthe track. The common position adjustment equipment may collectivelyvary the position of imaging and inertial sensors. Such equipment may bemounted internal to the overall system enclosure reducing the weightrequired to shift on a moving train of only the imaging and inertialsensors as opposed to moving the weight of the entire enclosure.

The common support may comprise at least one rail or runner. A housingfor one or more scanning sensor, e.g. a common housing, may be mountedto the runner.

The system may comprise an actuator for position adjustment relative tothe mounting. The actuator may be arranged for linear/lateral actuation,e.g. by way of a linear actuator or a rotor comprising a mechanism forconverting rotational/torque input to linear motion. The actuator may beelectrically powered, such as an electro-mechanical actuator. Theactuator may provide for the lateral adjustment of the imaging sensorsto remain in the same relative position with respect to the rail whilstthe vehicle is in motion.

The common support may be adjustably mounted to accommodate heightadjustment of the sensors and/or the system as a whole. Heightadjustment may be implemented to attain a predetermined height above thetrack and/or a rail thereof. Height adjustment may be implementeddynamically during use of the sensors or may be set at a predeterminedheight prior to use. Height adjustment may allow alteration of the fieldof view of one or more scanning sensor. Height adjustment may be used toeffect different modes of operation of the system, for example toinclude rail inspection or whole track inspection. Different heights maybe suited to inspection of different specific track component types.

The system may comprise a controller, e.g. mounted on the common supportand/or within a common housing. The controller may control any or anycombination of: the track scanning sensors; power management for thesystem, e.g. including charging of one or more battery; thermalmanagement of the system; data communications to/from the system, e.g.including alerts; lighting or other irradiation of the track for thescanning sensors. The controller functionality may be provided by one ormore processor. The scan data processor may perform some or allcontroller functionality or else a separate system controller may beprovided.

The rate of track scanning may be controlled according to the railroadvehicle travel speed. A predetermined rate of scan/image capture orvolume of scan data per unit distance may be set. For example, a rate ofpixel capture per mm distance along the track may be set. A pulsedsignal at a pulse frequency according to vehicle speed may be used tocontrol the scanning rate. Additionally or alternatively, the rate oftrack scanning may be altered according to user requirements and/orpredetermined track sections, e.g. according to different modes of trackscanning.

A vehicle wheel or drive shaft tachometer may be used to determinetravel distance/speed. A laser Doppler device may be used.

The system may comprise an irradiation/light source. A dedicated lightsource mounted on the common support may provide bespoke illuminationfor the purpose of the invention, e.g. arranged to illuminate a regionof the railroad track corresponding to the field of view of the trackscanning sensors. A linear light source array (e.g. a linear array ofLED's) may extend across the width of the common support and/or track inorder to provide uniform lighting across the track section beingscanned. Alternatively, light may be directed onto opposing sides ofeach rail of the railroad track.

The light source may be operated in a discontinuous, e.g. pulsed orintermittent, manner. The light source may or may not be pulsedaccording to the scan frequency of one or more sensors and/or vehiclespeed.

One or more scan sensor may comprise a filter, e.g. a light filter. Thefilter may be adapted to prevent unwanted wavelengths within the scandata and may for example be tailored to a light source of the system.The operation of the system may adjust according to the level of thelight received by the sensors. An aperture or filter of the/eachscanning sensor may be adjustable, e.g. according to the ambient lightlevel.

The system may comprise of an energy transmission source that isrequired for imaging sensors operating within a suitable portion of theelectromagnetic spectrum to image a target area. Sub 1 mm wavelengthradiation may be used, such as x-ray or terahertz radiation. Thetransmission and energy characteristics could be configured to maximizethe image contrast and ability to see the internal structure of theobject. The energy transmitter may be synchronized with the imagingsensor such that the reflected or transmitted energy from an object ofinterest is imaged by the sensor, e.g. in either a linescan or areamode.

The system may comprise a location determination device/system. Thetrack scan data recorded by the sensors may be logged with a locationrecord (e.g. a geographical location record) from the locationdetermination system. The location record may correspond to thesensor/vehicle location. Where a plurality of sensors are used thecorresponding scan data captured by the plurality of sensors may belogged with a common location record.

The location record may comprise a plurality of components (e.g.latitude and longitude) according to a geographic coordinate system. Thelocation record may additionally or alternatively comprise a local orrelative coordinate value, e.g. relative to the railroad track. Thelocation record may comprise a one-dimensional location record componentor value, e.g. according to distance along the railroad from a datumpoint. In any examples, the location record may be supplemented with, orsubstituted for, a time record (e.g. a timestamp).

The location determination system may comprise a vehicle travel distancesensor, such as a tachometer, and/or a track position sensor. This maybe used in addition to, or instead of, a GPS or other geographiclocation system. Combining multiple location determinationsystems/sensor types may be used to increase the accuracy of trackcomponent location determination. A track position sensor may comprise asensor for identifying track features indicative of known/predeterminedtrack locations, e.g. fixed datum locations. One or more scanning sensorcould be used for this purpose or else a near-field wirelesscommunication transmitter receiver. An RFID sensor, for example, couldbe used to detect RFID tags mounted on the track at known locations. Alookup table of known tag locations may be used to determine assetand/or image sensor location.

The inertial data sensor(s) may comprise any, or any combination, of:accelerometers, gyroscopes, inclinometers and other electromechanicalsystems to generate data on three dimensional position, velocity,acceleration, and roll, pitch, and heading. The inertial data combinedtogether with satellite information on vehicle position, and with tachodata, provides enhanced accuracy on positioning of measurementsincluding tunnels. It may be further combined with laser basedmeasurements of rail and surrounding track to provide track geometrymeasurements in real time.

The system may comprise a thermal management device, e.g. a coolingand/or heating device. A fan, peltier air cooler or liquid coolingsystem may be used. A common housing may comprise one or more vents topermit airflow through the housing interior.

The system may comprise a local power source, such as a battery. Thelocal power source may allow at least some, or all, functions of thesystem to operate in isolation of an external power connection. Forexample, the battery may allow processing of received scan data, e.g. inorder to complete scan data analysis after power supplied by therailroad vehicle has been cut off. The local power source may be chargedby vehicle motion, e.g. vibration and/or wheel motion.

The scan data processor may comprise a plurality of processors/chips,wherein at least one processor is arranged to log captured scans/imagesand associated location data in real time in the data store. Saidprocessor may be arranged to collate image/scan and/or associated datafrom a plurality of sensors/sources.

At least one processor may be arranged to process the captured scan datato identify track components substantially in real-time or with a slighttime delay, e.g. near-real time. At least one processor may be arrangedto perform image analytics on images captured by the scan sensor(s).Scan data may be logged in parallel with analytical processing thereof.A central controller may determine which of the processes are carriedout concurrently according to data input rate and/or processing rate.Any or any combination of the processors may operate automatically uponreceipt of the relevant data.

Scan data storage may comprise indexing scan data with a location and/ortime data record. Scan data storage may comprise storing scan data as aflat (e.g. binary) pixel data format, or as compressed images withconventional formats such as JPEG, e.g. with a location identifier. Forflat file format, scan data file header information may be added at asubsequent processing stage (e.g. not in real-time or near real-time).

At least one scan data processor may be arranged to process the recordedscan data so as to analyze track component status either on board thecommon support structure, on board the railway vehicle, or else at aremote location, e.g. at a time after scan data acquisition. The systemmay output track component identification, location and/or status inreal-time, e.g. such that there is substantially no delay or negligibledelay between when the track components are visible within the field ofview of the scanning sensors, and their detection by the automated scandata analyzing system. This allows for the operator to view trackcomponent identification and/or status as the vehicle passes thosecomponents in real-time. The scan processor may output track componentstatus either immediately or with a relatively short time delay afterimage capture, e.g. in near real-time. In any example of the inventionthe recorded scan data processing time may comprise a relatively shortertime period or speed compared to the travel time or speed of thevehicle, such as for example a fraction of the travel time/speed, e.g.less than a half or quarter of the vehicle travel time/speed, or anorder of magnitude or more less than the vehicle travel time/speed, atnormal vehicle speeds. In case of near real-time, there is a short delaybetween when the sensors are able to view a track component, and when itis registered as found with its measured properties within a databaseused by the scan data processor. This delay can be variable based on thehardware capability and complexity of scan data analysis software.

The data store may comprise a non-volatile data store comprising adatabase comprising raw scan data obtained from the sensors and afurther database comprising track component classification, trackmeasurements and/or status data logged with a location recordcorresponding thereto.

The data store may comprise a processed scan/image data store and abuffer. The processed scan data store may comprise scan image files andassociated track component classification and/or status data. Real-timeor immediate processing of data as referred to herein may occur at therate of scan data acquisition, e.g. substantially avoiding use of thebuffer. The processed scan/image data store may comprise location datacorresponding to the stored images.

The scan data processor may comprise a central processor and either orboth of a field programmable gate array and a graphics card. The abilityto divide up the processing between different processors is beneficialin defining a hierarchy of processing tasks.

The scan data processor may comprise a sensor data collation/managementmodule and data analysis module. A more detailed data review module maybe provided as part of the system but may be only selectively employedby a central processor. A modular approach to data processing may allowa different combination tasks to be performed selectively for differenttrack assessment jobs. Not all tasks need be performed for all uses ofthe system. For example, some processing stages can take precedence andalways be performed (e.g. in real time), such as scan data indexing,whilst one or more further data analysis stage may be optionallyemployed.

Dimension and/or shape measurement of track components may be matched topredetermined shape profiles, e.g. in order to determine the identity oftrack components, measure them, identify their defects, identity missingcomponents where expected, or trigger a further data analysis withanother sensor. One, two or three dimensional shape model constructsand/or analysis may be used. Shape profiles may be further evaluatedusing their size, shape and orientation. Any such parameters may be usedin combination with inertial data to determine rail orientation,incline, super-elevation, twist as well as determine track gauge andcurvature parameters.

A confidence score may be determined for, and/or assigned to, a trackcomponent determination by the system according to a degree of the matchbetween one or more geometric feature/profile and/or surface propertyfeature of a track component identified in the recorded track scan dataand one or more predetermined component features. It has been found thatthe combination of shape matching and color/texture matching yieldsimproved certainty in component identification and condition analysis.

The system may comprise a plurality of track component detector, e.g.different types of classifier. One classifier may or may not comprise arule-based classifier, e.g. employing statistical and/or semantic rulesfor component matching. One asset classifier may or may not comprise atemplate classifier, e.g. matching a component shape/surface propertyusing one or more correlation-based matching method, such as a neuralnetwork or genetic algorithm. One component classifier may or may notcomprise a feature matching tool, e.g. by which pixel clusters arestatistically matched to component attributes/features in predeterminedcomponent recognition tables.

Template matching may be used for track componentdetection/identification. The list of predetermined component types maycomprise a list of predetermined component templates. Predeterminedtemplates may comprise one or more geometric feature and/or one or moresurface property feature. Geometric template features may comprisecurvature, edge and/or dimension features. Surface property features maycomprise color, brightness/intensity, and/or surfaceuniformity/variation.

A location determining system for images captured by the sensor and animage processor, the image processor comprising an asset classifier fordetecting an asset in one or more captured image and classifying thedetected asset by assigning an asset type to the detected asset from apredetermined list of asset types according to one or more feature inthe captured image, and an asset status analyzer for identifying anasset status characteristic and comparing the identified statuscharacteristic to a predetermined asset characteristic so as to evaluatea deviation therefrom. The asset analyzer may further evaluate depthmeasurement, surface profile and/or inertial data to identify the threedimensional position of the asset in space, and to use this informationfor determining track abnormalities.

The scan data processor may serve as a novelty/anomaly detector. In theevent that the processor identifies a detected component/feature thatdoes not meet criteria for assigning a predetermined track componenttype, the asset classifier may log an instance of novel objectdetection. The scan data processor may log any or any combination of:scans/images in which the unrecognized object is identifiable; alocation of the unidentified object; processed scan data (such assurface property and/or profile) for the unidentified object. This logmay be later analyzed to create a new component type or assign anexisting component type to the object.

An alert module may be provided, which may receive the output of thescan data processing and determine whether one or more alert conditionis met. Alert criteria may be set based on component type/status and/ornovelty/anomaly detection. Semantic knowledge comparison may beperformed prior to alert output, e.g. to avoid false positives, for atleast some component types.

The scan data processor may be accompanied by additional hardwareresponsible for image or laser data compression. In some cases, thesensor modules may have a built-in module for data compression orperforming a limited set of analytics.

The scan data processor may perform track component change analysis. Thescan data processor may compare current scan data with prior scan dataat the same location or a previously determined component statuscharacteristic, e.g. a geometric or surface characteristic. Changes intrack component orientation, shape, edge and/or color may be monitored.The system may log changes/deterioration of track components, bothinstantaneously (i.e. between two successive passes of the component)and/or over extended periods of time, such as days, weeks, months,years. Depending on data storage capability, one or more statuscharacteristics may be logged for comparison with later determinedstatus characteristics. Comparison of simple asset status characteristicvalues may avoid the need to re-process previously logged image data.Previously logged component status characteristics may be stored in thescan data store or another on-board data store, for comparison inreal-time or near real-time.

The results of track evaluation showing track abnormalities andmeasurements may be transmitted in the unattended mode of operation to aremote location, e.g. using a cellular network. A cellular transmitterrouter combined with an antenna on board the vehicle could be connectedto the system for transmitting live data. In the absence of satellitecoverage, data may be buffered for transmission until it becomespossible to transmit data. The remote location may consist of data webservers that store the received information and pass on the analysis tothe end-user through the use of a web portal in real or close-to-realtime.

According to a second aspect of the invention, there is provided arailroad track inspection method corresponding to use of the system ofthe first aspect.

According to a further aspect of the invention there is provided a datacarrier comprising machine readable code for the operation of a trackscan data processor in accordance with the system or method of the aboveaspects.

Any of the optional features defined above in relation to the firstaspect of the invention may be applied to any further aspect.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the application are setforth in the appended claims. However, the application itself, as wellas a preferred mode of use, and further objectives and advantagesthereof, will best be understood by reference to the following detaileddescription when read in conjunction with the accompanying drawings,wherein:

FIG. 1 shows a schematic section view through a housed rail trackinspection system according to an example of the invention;

FIG. 2 shows a three-dimensional view of a mounting system for mountinga rail track inspection system to a train according to an example of theinvention;

FIG. 3 shows an example of a passenger train to which a system accordingto an example of the invention can be mounted as an integrated unit;

FIG. 4 shows an example of a removable processing unit (RPU) accordingto an example of a system according to the invention;

FIG. 5 shows a schematic arrangement of data flows between differentcomponents of a system according to an example of the invention in use;

FIG. 6 shows a three-dimensional view of a section of rail track,including examples of track features that may be inspected by use of theinvention;

FIG. 7 shows a three-dimensional view of a section of rail trackincluding a junction or switch which may be inspected in examples of useof the invention;

FIG. 8 shows an example of a digital image taken by a system accordingto the invention of a rail side and surrounding track;

FIG. 9 shows an example of a digital image taken from above by a systemaccording to the invention of a rail head, fastener and plate area;

FIG. 10 shows an example of a further type of image, i.e. alaser-derived image, of an interface region between a railroad vehiclewheel and a rail captured by a system according to an example of theinvention;

FIG. 11 shows examples of track geometry and rail profiling measurementsmade using examples of the invention;

FIG. 12 shows a three-dimensional view of further example of a systemcomprising imaging and inertial sensors coupled together on a commonsupport structure; and

FIG. 13 shows an example mode of use of the system for inspecting atunnel.

While the system and method of the present application is susceptible tovarious modifications and alternative forms, specific embodimentsthereof have been shown by way of example in the drawings and are hereindescribed in detail. It should be understood, however, that thedescription herein of specific embodiments is not intended to limit theapplication to the particular embodiment disclosed, but on the contrary,the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the process of thepresent application as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Examples of the invention described hereinbelow concern the use of ahoused system for surveying railroad track, herein termed a “TrackVue”system. All the equipment required for scanning, processing and loggingthe visual and/or geometric features of railroad track are provided witha common support structure so as to allow for a system that can beinstalled on passenger trains and/or freight trains as well as, orinstead of, being installed on dedicated inspection vehicles. A singularhoused unit or installation of this kind is well suited for retrofittingon existing trains and can offer simple installation and operation.Systems according to examples of the invention may provide so-called‘plug-and-play’ functionality when compared to the systems used in theprior art. The advantages of the support of the various differentsensors on a common structure that is mountable to the exterior of arailroad vehicle are described hereinbelow.

Turning firstly to FIG. 1, the system 10 includes a plurality of trackscanning sensors, which in this example comprise a plurality of imagingsensors 12. The imaging sensors are capable of recording electromagneticradiation in the visible range, i.e. visible light, to show the externalsurface of a track object, but may additionally or alternativelyencompass infrared wavelengths or wavelengths in the x-ray or terahertzspectrum to show the internal structure of a track object. An activelight source for visible spectrum imaging or an energy projection and/ortransmission device, shown schematically at 13, may be required forx-ray and terahertz imaging. In some examples of the invention, thermalimaging may also be accommodated. Both visible and thermal radiationwavelengths may be sensed at once by a common sensor and subsequentlyfiltered to separate the visible and thermal/infrared images.Alternatively, different individual sensors may be mounted at one ormore imaging sensor unit 12 with physical filters to control thewavelengths of radiation detected by each sensor. In either example,separate thermal/infrared (IR) and visible light images can be recorded.In other examples, it is possible to additionally or alternatively usenear-IR sensors/filters.

The number and configuration of imaging sensors placed can be tailoredto cover the entirety of the railroad track, as will be discussed infurther detail below, or just specific portions thereof as required. Thekey properties of each imaging sensor comprise any or any combinationof: whether it is color or monochrome; horizontal and vertical imageresolution; scanning frequency in hertz; the type of interface withimage acquisition devices including GIGE, CAMLINK, USB, etc.; sensortype and size; and, any inbuilt intelligence to perform analysis, datacompression or dynamic adjustment of its imaging parameters to cater tochanges in the environment. The sensors can be chosen to suit theenvironment for imaging on a mainline passenger, freight, metro,underground or dedicated inspection train, as well as on rail-adaptedvehicles (e.g. hy-rail) and trolley-based platforms such that theirimaging sensors can cover the overall area of survey and inspection asdesired for a particular application.

Each imaging sensor 12 in this example comprises a lens 14 and filter16. The lenses 12 can be of fixed or variable focal length and definethe field of view required for image capture. Appropriate cut-offfilters 16 can be provided so as to limit the range of electromagneticwavelength to which the sensor is exposed in use. This may reduce theexternal light interference from certain wavelengths.

In the example shown in FIG. 1, three imaging sensors 12 are shown forillustration. A central imaging sensor 12A is positioned generally abouta rail 18 to be inspected in use, and two flanking imaging sensors 12Band 12C are positioned on either side thereof. The central sensor 12Aprovides an above view, i.e. a plan view, of a rail 18 in use, whereasthe flanking 12B and 12C sensors are obliquely angled relative theretoand provide a view of the remainder of the track to each side of therail. The angular offset between the sensors 12 is substantially in acommon/vertical plane. The angular offset of the sensors 12B and 12C maybe roughly 45° off the axis of alignment of sensor 12A, although theoffset may be adjusted according to the field of view by virtue of lens14 and so may encompass wider or narrower oblique angular offset. For apractical implementation, the number and position of sensors may bevaried to cover the entire width of the track that needs to be inspectedprovided that the system mounting does not infringe required track andvehicle clearances.

The fields of view of the sensors 12 may be overlapping to ensure fullcoverage. In this regard, it will be appreciated that the arrangement ofFIG. 1 is for scanning a single rail 18 including the flanking railroadtrack portions on either side of that rail, and that a furthercomplement of sensors is provided for the adjacent rail. Only a singleset of sensors is described for conciseness and it is assumed that thefurther set of sensors for the adjacent rail will match the sensorsdescribed in relation to FIG. 1. The different fields of viewcollectively cover the entire width of the railroad track from one endof each sleeper to the opposing end. Thus imaging is performed for thetrack region on either side of the rails, e.g. with the option ofsleeper ends, and not just the rails themselves.

In the example of FIG. 1, the imaging sensors 12 are digitalscanners/cameras in the form of linescan sensors. The linescan imagingsensors 12, which may operate within and/or outside of the visiblespectrum, thus have a narrow/linear field of view arranged laterallyacross the railroad track in use, i.e. relative to the direction of thetrack or a longitudinal axis thereof. Scanning a sequence of narrowlines in this manner allows a collection of lines to be built up andconcatenated to form an image. The number of pixels in one linear scanis determined by the imaging sensor resolution. In other examples of theinvention, it will be appreciated that areascan imaging sensors could beused in addition to, or instead of, the linescan sensors describedabove.

A suitable imaging sensor 12 can be color or monochrome (grayscale).

The field of view of the imaging sensors comprises the track directlybeneath the system 10, i.e. beneath the railroad vehicle to which thesystem is mounted. Thus the system has a top down view of the track.However the internal imaging and laser sensors may be positioned topdown or at an angle to cover the side of certain track assets such asrails and top track surfaces. The field of view of each sensor could bemodified by altering the lens position 14 and/or its mounting positionif required. The recorded track image is thus a digital representationof the light reflected from the various track components in the scene,having a pixel density according to the resolution of the imagingsensors being used.

For a thermal imaging sensor, which may comprise a suitable thermalcamera or a thermopile array, a digital image representing the heatsensed is recorded. The temperature values recorded are translated intoan image representation that depicts the change in temperature acrossthe scene, e.g. which could be output on a visual display to a humanuser, and is suitable for automated image analytics. The output of eachof thermal and visible light sensors is therefore a sequence ofimages/frames, each comprising an ordered array of pixels covering thearea of interest, each pixel having an associated color, brightnessand/or heat energy (temperature) value.

For an x-ray or terahertz imaging sensor, which may be coupled with anenergy transmission source, a digital image representing the amount ofenergy absorbed, reflected or transmitted through a track asset may beconstructed as a linescan process or as an area image. Such an imagewill be able to show the internal structure of the target object, forexample including internal cracks, voids and material condition forrails and sleepers

The TrackVue system allows for adjustment the imaging sensor operationparameters, e.g. dynamically or through applied software control, suchas aperture, exposure and gain settings in response to the amount oflight detected by its internal sensor, thereby allowing for therecording of better quality images to compensate for any illuminationchanges over the imaged area. The system allows for adjustment of thesensor operation substantially in real time according to ambient changesin light levels by use of a suitable controller as will be described infurther detail below.

The TrackVue system 10 includes a dedicated light source forilluminating the region of the track being scanned. This may be achievedby continuous illumination of an area of the track that is in theimaging sensors 12 field of view or else by pulsing/flashing the lightsource only when an image is being captured. FIG. 1 illustrates theposition of high intensity LED lights 22 that are suitable for thispurpose. The lights may be split into modules that light the top of therail and track, and side of rail areas. The lights are integrated withinthe overall system assembly housing 20 such that they are mountedrelative to said housing 20 and are powered via the system as will bedescribed below. The light source may be provided as one or more stripsof individual lights, e.g. corresponding to the image captured from thelinescan sensor. The lights can be selected for specific wavelengths orcan be pure white so as to enhance the quality of imaged objects indigital images.

The output of the light source is typically sufficient to provide therequired lighting for operation in the absence of ambient/natural light.The sensor aperture, exposure and/or gain parameters may be used tosubstantially remove ambient effects on the sensor readings. In oneembodiment, it has been found that directional visible lighting ontocertain track features may be desirable to determine asset identity andits condition. In examples where some sensors operate in non-visiblespectrum, additional energy transmission sources may be necessary togenerate x-ray or terahertz beams to bounce off or transmit through thetarget of interest that can be detected by an imaging sensor.

In addition to the digital imaging sensors 12, the example of FIG. 1comprises one or more laser device 24 for use in obtaining a furthersource of sensor data for use in surveying the railroad track. In thisexample two laser devices 24 are provided for each rail 18. Each laserdevice 24 may be laterally offset from a central axis of the rail 18 andmay be obliquely angled relative to vertical so as to image a side ofthe rail 18 as well as a portion of the rail head.

A suitable laser scanning system may comprise either a laser emittingdevice 24 on its own, or a laser device 24 having its ownimaging/scanning sensor assembly. The laser-sensor dataacquisition/processing components could be integrated with dedicatedsensors within the laser device 24 itself, in a separate dedicated unit,or could be comprised within track imaging sensors 12 as shown inFIG. 1. In any example, the laser emitting device 24 (i.e. thelaserhead) is commonly mounted with, and contained within, the overallsystem housing 20 and is powered thereby.

A linear/beam laser may be used for geometric assessment of trackcomponents. A variety of laser beam patterns may be used including spot,line, and grid. The laser device may have an inbuilt processor or anexternal processor may be used to determine a three dimensional surfaceprofile, which may be further combined with vehicle inertial data todetermine the three dimensional positions of various track assets and/orthree dimensional distances between two points in the scan area.

Each laser device 24 emits a narrow beam of laser on the object ofinterest for surface topology measurement. The laser thus forms a regionof irradiation, i.e. a linear path or a region across the rail and theadjacent track components, the reflection of which is detected by thecorresponding sensor so as to interpret the corresponding geometry ofthe reflecting surface(s). Thus a linear section or a wider area of therail and any adjacent track components can be scanned, depending on thelaser system implemented.

The length, width and orientation of the laser beam pattern can bemodified to suit specific applications. The power of the laser isoptimised to generate a beam pattern that shows sufficient contrastbetween where it falls on the track, and its immediate surroundingareas.

The imaging sensors used for laser beam imaging can be configured togenerate coordinate data for the beam position within a field of view,e.g. binary data comprising horizontal (x), vertical (y) and depth (z),and/or generate a two dimensional grayscale image showing the laser beamagainst its surroundings which provides a reference to the identity ofthe object under measurement. A grayscale image requires furtherprocessing to generate depth data for each point on the laser beamwithin the image with supplementary processing of background image tounderstand the identity of assets overlaid by the laser beam.

Dedicated laser imaging sensors for use with devices 24 could use areascan imaging at high frame rates and can be pulsed along with lasers.Pulsing as an option can be set in control circuitry either containedwithin assembly or a further control unit for the system as will bedescribed below. Pulsing may serve to reduce laser emission, reduceoverall power consumption and keep the lasers cooler than possible withconstant emission.

Based on the above description, it will be appreciated that the scanningof railroad track may accommodate any, or any combination, of visiblelight (camera), x-ray or terahertz imaging camera and energy transmittersource, depth (e.g. laser) and/or thermal scanning sensors, any of whichmay output surface or subsurface image or surface profile/coordinatedata to be used in the surveying system. Whilst the examples describedherein comprise a full complement of imaging sensors, it is intended inexamples of the invention, that individual sensors or sensor types willbe selectively operable, such that not all sensors are required to beoperable at all times. One or more sensor may be triggered for operationat only selected times, or for only certain types of asset inspection,whilst one or more other sensor may be always used. The system isdesigned such that the laser light source, LED light source and energytransmitter does not contaminate the readings taken by the othersensors.

In FIG. 1 there is also shown an example of the image processing andancillary equipment for operation of the track surveying system, mountedwithin common housing 20. The overall system is broadly split into threeseparate compartments/modules that are provided together a single unitfor installation on a train. These are: (a) The main housing 20 of theTrackVue enclosure that houses sensors, lighting and other ancillarycomponents; (b) A removable processing unit (RPU) 30 that ismechanically and electrically coupled to/within the main housing 20 foruse and consists of data processing, storage and control hardware; (c) Abattery 28 that also integrates with the main housing 20 to allow forsystem operation in addition to the use of power supplied via therailroad vehicle.

The main housing 20 defines a hollow enclosure to which any of theaforementioned scanning equipment 12A, 12B, 12C, 24 and any associatedlighting 22 can be mounted. Corresponding openings/windows are providedin the housing 20 to allow imaging of the track components externally ofthe enclosure 20. The internal mounts for the scanning equipment withinmain housing enclosure may be adjustable, if needed, to allow for changein their viewing angles of the imaging sensors. Motorised/electricalangular adjustment mechanisms may be integrated into the camera/sensormounts. This may be in addition to or instead of the sensor actuationequipment discussed in further detail below in relation to FIG. 2.

Each scan sensor and/or laser device 24 is typically placed behind atransparent window 26 which protects the sensor from the outsideenvironment. The windows 26 are mounted in the wall of a commonenclosure 20. A toughened glass or other suitably transparent materialmay be used for the window.

The shape of the housing enclosure 20 in this example is such that itprovides adequate clearance from the rail 18, whilst also offering therequired field of view for each scan sensor. Therefore a contoured formfor the housing 20 may be used as shown in FIG. 1 in which a centralsection of the housing wall (e.g. in the vicinity of the sensor 12A) isrecessed relative to adjacent wall sections on each side thereof. Thusthe housing provides on its underside a central inverted gulley, whichis aligned with a rail 18 in use, e.g. with two ‘lobes’ or downwardlyprotruding housing portions on either side thereof. The windows providedin the enclosure 20 may thus comprise window portions at differentangular orientations to accommodate the different viewing angles of thedifferent scanning sensors and/or the orientation of the enclosure wallwhere the window is located. In another embodiment, a single cuboidalenclosure with no recessed contour that contains all required equipmentmay be used.

The example of FIG. 1 shows a single enclosure 20 containing all thesensors required for scanning of a single rail and the surrounding trackcomponents. It will be appreciated that the overall system may comprisetwo sets of scanning equipment/sensors in respect of two rails to bescanned simultaneously. The system may thus comprise two or moreenclosures or housing structures for each set of equipment, which may beprovided as a commonly mounted structure to the railroad vehicle.Alternatively, the system could comprise a single enclosure spanningboth rails. The ancillary equipment shown in FIG. 1 may all beaccommodated in a single enclosure or split between a plurality ofenclosures sharing a common mount to the vehicle as necessary.

The main housing 20 has a mount 32 for fixing the housing onto arailroad vehicle. In this example, the housing depends downwardly froman underside of a railroad vehicle and so upper wall 34 of the housing20 has a mounting bracket 36 depending therefrom.

The cooling of the interior of both the main housing 20 and also the RPU30 is an important operational consideration for dissipation of heatgenerated by the imaging sensors, laser, LED lights, as well as anycomputational equipment. The exterior of TrackVue housing 20 will be aircooled by motion of the train in use and so conductive cooling of anyheat sources can be accommodated by thermally coupling the heat sourcesto the external wall of the housing 20. Depending on the design of thehousing 20, the system may comprise one or more thermal managementsystem/device 58, which may comprise of a liquid cooling systemconsisting of liquid reservoir, pumps and liquid blocks that can bemounted on components that need to be cooled. Fans, vents fins or thelike, may additionally or alternatively be provided on the housing 20,e.g. at location 38 in FIG. 1. Any such cooling arrangement may promoteheat loss to the air flowing over the exterior of the housing 20 duringmotion of the railroad vehicle by increasing the surface area exposed tothe passing airflow and/or directing airflow into/over the housing 20.As well as a cooling function, the thermal management system 35 mayfurther comprise a heater that may be switched on by the controlcircuitry 42 when the enclosure temperature falls below freezing and isbelow the minimal operational temperature of the system components. Theheater would warm up the reservoir fluid and circulate warm liquid toraise component temperatures in freezing conditions. In this manner, acommon thermal management system may serve to ensure that the system canoperate in both hot and cold conditions.

One or more cooling fan 40 can be provided within either or both of themain enclosure 20 and RPU 30 so as to promote convection cooling. Ifnecessary, either or both of the main enclosure or RPU 30 could beprovided with a liquid cooling system in the event that air cooling isinsufficient alone to maintain the internal temperature at a desiredlevel.

The main housing further comprises control/management circuitry 42 whichmonitors trigger/pulse signals, power supply, devices within theTrackVue system 10 and any environmental readings. The managementcircuitry 42 is responsible for the operational state/health of theequipment and can output control signals to regulate their use so as toensure equipment operation is maintained within desirable limits. Thecircuitry is responsible for managing a number of tasks including:

-   -   a) Monitoring and regulating internal temperature and humidity        of TrackVue with its on-board temperature and humidity sensors.        In case these parameters exceed their required threshold, the        control circuitry can shut down the power to TrackVue or to        individual devices therein. In such an event, an alert will be        sent to a display 44 as shown in FIG. 3 of a monitoring console        within train 46 and/or to any other relevant        communication/monitoring equipment through a Train Information        Management System.    -   b) Monitoring the levels of battery charge and for charging it.        This applies to the main battery 28 and/or a battery 48 internal        to RPU 30. Any alerts of battery faults or insufficient charge        may be reported by alerts as described herein.    -   c) Modifying the incoming voltage power supply to suit the needs        of imaging sensors and laser equipment and for redistributing it        as needed.    -   d) Monitoring and modifying/improving the signal quality of the        incoming trigger/pulse signal for controlling the rate of        visual, thermal and/or laser scan data acquisition.    -   e) Permitting and inhibiting camera and laser equipment        operation such that those devices are only useable once the        vehicle is in motion.    -   f) Providing an end-user with information on the health status        of various TrackVue components through the LCD display 50 on the        housing 20 itself, the monitoring console display 44 in the        train cab (FIG. 3) and/or another remote console. Rather than        the track survey data, this operational data concerns the system        10 health and may be used to understand operational issues, plan        maintenance, etc.    -   g) Pulsing LED lights or lasers in order to reduce power        consumption or reduce the heat generated by their use.

In various embodiments of the invention, the main housing 20 comprises alocation determining device or module 54. This may comprise a standardGPS or Differential GPS device which records the latitude and longitudeposition of the vehicle, e.g. at a set frequency.

In various embodiments of the invention, the main housing 20 maycomprise operational control devices, such as any, any combination, orall of:

-   -   A power supply unit 56 to convert an input current (e.g. at 24        VDC) to a supply suitable for the system, e.g. including cameras        and lasers, (such as at 12 VDC or 5 VDC);    -   A cooling/heating device 58 to regulate temperature in the        housing, e.g. to cool heat-generating electrical components in        use, and/or to warm up the housing interior to the minimum        operational temperature by circulating warmer liquid in case the        unit temperature drops below a minimal temperature threshold in        freezing conditions;    -   A dehumidifier unit 60 that is able to absorb the moisture from        the air inside the unit.

The main housing has electrical/data connectors for communication ofdata signals with the railroad vehicle and/or powering the TrackVuesystem 10. A minimum number of external connections may be provided tosimplify installation of the system and may comprise a single powerconnector for the system 10 as a whole and a single external dataconnector port. However a practical implementation of the system couldcomprise any, any combination, or all of:

-   -   one or more connectors 62, such as internal and/or blindmate        connectors, which allow for the RPU 30 to be mated with the main        housing 20. The connectors 62 allow for transfer of data and        power.    -   an external data connector 64 for supply of trigger signal from        a vehicle wheel encoder or other suitable vehicle speed input        signal;    -   an external power connector 66 for the taking power from the        main power supply coming from the vehicle at an appropriate        voltage accepted by TrackVue;    -   an optional connector 68 for location data or other data input        from an external device, e.g. RFID scanner or a third party        location detection system aboard the train;    -   a connector 70 for high speed data transfer through a wired        connection, e.g. to the train data bus. This can be used where        high volume real-time data needs to be transferred to an        external storage on-board the vehicle. This may be required by        the end-user to either carry out a more detailed, off-line data        analysis, or to review all images collected from the track.    -   a wireless connection through the cellular data router        (transmission device) 84 which uses an antenna to transmit data        wireless in real or close to real-time to a remote location        which allows the end-user to receive information on track        condition and system performance through a web-portal.

In its current format, the system allows for the use of battery powerfor short surveys because of limited capacity, and uses power from thevehicle or mains power to charge it. As battery technology continues todevelop, it is expected that longer surveys can be carried with batterypower in the future. The current design allows for the battery 28 to beswapped easily from its own compartment in the field and replaced with acharged one to carry out recording. The battery charging and capacitystatus can be displayed on the LCD display 50 and also relayed to theoperator console 44 (FIG. 3).

The scan data processing equipment 72-78, associated software modules 79and data storage 80 are housed within a separate RPU 30 housing. RPU 30contains all computational equipment for data capture and processing.The RPU 30 comprises a self-contained unit which can process image dataindependently, provided it is supplied with the relevant incoming imagedata stream. For this reason, the RPU is provided within its owndedicated housing that is removable/replaceable as a module from themain housing 20.

The RPU 30 in this example comprises computer motherboard 72, high speedprocessor 74, Field Programmable Gate Array (FPGA) or frame grabber 76,graphics card 78, and a non-volatile data store 80, e.g. comprising oneor more data disks, on which are provided one or more software modulefor processing captured visual, thermal, laser, location and/or inertialsensor data. Thus whilst the software modules 79 are shown as a separateentity in FIG. 1, those relevant processor instructions may be stored,e.g. as executable code, on any suitable memory device within thesystem. The data store 80 also typically stores the track scan sensordata itself, location data and/or any processed track inspection (i.e.asset classification, defect and/or status) data.

An internal battery 48 for the RPU 30 is provided to ensure that, as aminimum, the internal processing components can be gracefully shut downif the unit is disconnected from the main housing battery or externalpower supply. Ideally the internal battery 48 would also allow continueddata processing, i.e. for image processing jobs already commenced, evenif disconnected from external power. The internal battery may also powera communications module for transmission of any relevant messages/dataprior to shut down. The battery may power the entire system for a periodof time. As battery technology improves, inspections may be performedentirely under battery power.

The RPU 30 has its own communication module 82, typically comprising anda conventional wired or wireless transceiver. The module may allowcommunications to the vehicle operator in an attended mode of operation,or otherwise to an Operational Command Centre (OCC) in unattended mode.Such a communications module could additionally or alternatively beprovided in the main housing 20 outside of the RPU. In both cases, thedata related to analysis or alerts can also be sent by this unit to theTrain Information Management System (TIMS). In addition, a 3G/4Gwireless data connection device 84 in the main housing 20 allowsexternal access to TrackVue. It may also be possible to put device 84for wireless data transmission outside of the main housing 20, orelsewhere on the railway vehicle, if it improves data transmissionespecially if the length of cable between the device 84 and its antennaon the train is long and attenuates transmission signal strength. Thewireless connection can also be used for remote access to performdiagnostics, software updates, and repairs of the unit.

The communication module 82 may serve as an alert transmission unit forsending any alerts due to an adverse track or equipment status detectedby either the control circuitry 42 or by the processing equipment withinthe RPU 30, to a remote location either using wireless or wiredconnection. The alert may relate to the condition of the system 10itself, or the track being surveyed.

To allow self-sufficient operation, the RPU 30 may also comprise any ofa fan 40 for cooling the unit, thermal management device 58 and/ordehumidification device 60 for absorbing unwanted moisture in theinternal compartment. The RPU 30 can be liquid cooled/heated by usingblindmate liquid connectors from the system 38.

The RPU uses blindmate connectors 62 to attach to the main housing 20 ofTrackVue body. This allows the RPU to be detached from the TrackVue asrequired by the operator and can be taken to a back an officeenvironment for data processing as will be described below. The RPUitself forms a completely sealed assembly for outdoor use. The RPU mayhave a handle (not shown) to aid removal. Status information related toRPU 30 or messages from control circuitry can be displayed directly on atouch panel display 50 which is visible to a human operator wheninspecting the system.

FIG. 2 shows an example of a mounting system for TrackVue 10 in which apair of housing enclosures 20 are mounted to a common support structure84. In certain embodiments, a single housing enclosure may be mounted tothe vehicle. The support structure 84 of FIG. 2 may be used instead ofthe fixed mount 32 described above in relation to FIG. 1. The supportstructure 84 extends laterally relative to the rails 86 in use such thatthe relevant sensors can be held in relation to each rail. The supportstructure 84 comprises mounting members 88, e.g. so as to define amounting frame structure for the system 10 as a whole, which attaches toa vehicle in use. Multiple mounting points may be defined on the frameand/or members 88 which can be attached to corresponding mounting pointson the vehicle (not shown) using conventional fasteners, such as bolts.

The members 88 take the form of elongate beams so as to provide strengthto the mounting structure and also a common support to ensure thecorrect spacing between the scanning sensors for each rail 86. In thisexample the mount comprises a panel member 89 having a frontal lip orwall section 90 in front of housing(s) 20.

FIG. 2 also shows the data connectors 64, 70 and power connector 66discussed above for operation of the TrackVue system 10.

The field of view of a scanning sensor contained within the housing 20depends on the position of mounting of the housing 20 on the vehicle,the position and orientation of the sensor within the housing 20, andthe properties of its lens.

As the vehicle moves, the field of view of the sensor with reference toa fixed position on the track, such as the position of the rail, canchange because of track curvature and lateral movement of the vehicle onthe rails. The amount of change to the field of view of a sensor dependsalso on its distance from the vehicle wheel set. If the track curvaturedoes not cause for the rail components of interest to significantly goout of the field of view, the scan data analysis software 79 (FIG. 1)will be capable of their accurate detection and measurement. However formuch higher track curvature, the sensor field of view could lose sightof assets of interest. One option to mitigate this would be mountthe/each housing 20 as close to a vehicle wheel as possible, e.g. eitheron the bogie or close to it. In cases where this is not possible, andhigh track curvature is an issue, it would be advantageous to provide asystem for altering the field of view of the sensors. In this regard,each sensor could be individually actuable to keep the relevant trackcomponents within the field of view, e.g. by actuation of a lens orviewing aperture to widen/narrow the field of view or else usingelectro-mechanical actuators to adjust the orientation of the scanningsensors. Additionally or alternatively, the sensors' field of view couldbe adjusted collectively as discussed below.

In this example, the mounting system 84 comprises an actuation unit 92for the TrackVue system 10 as a whole. The actuation unit 92 is referredto herein as the ‘TrackGlide’ unit as shown in FIG. 2. The mountingsystem 84 comprises one or more runner 94, via which the housing 20 issupported, e.g. suspended, in use. The housing 20 may comprise a bearingstructure 95 for mounting on each runner 94 to allow low-frictionmovement along the runner. The runners 94 extend laterally relative tothe track 86, e.g. being aligned with mounting members 88 and allow thehousing 20 to be actuated in a constrained, linear manner as a movingplatform so as to remain correctly positioned relative to the rails 86.

The actuation unit 92 comprises one or more linear actuators 96 thatattach to support 98, which may comprise a linear support. Controlledactuation is achieved using a suitable electrically-powered drive, suchas a stepper motor, by way of an encoder 100. The actuation unit has anelectrical connector 102 for powering the unit and a data connector 104for receiving operation commands from an external source such as theTrackVue system 10, e.g. to control the distance and direction ofmovement of the overall TrackGlide unit 92.

In use, the electrical signal to control movement is generated by thecontrol unit 42 (FIG. 1) under the direction of software 56 which usesone or more scanning sensor (e.g. a laser sensor input and/or a digitalimage input) to decide on the position of a key reference feature/pointon track, such as an edge of the rail. The control unit 42 uses thelocation of the reference feature to estimate the lateral movement ofthe vehicle relative to the track that must be compensated by moving theTrackGlide unit 92 (FIG. 2) in the opposite direction. One or moreinertia sensor could be used as an input to the control unit 42 in otherexamples of the TrackGlide system.

The TrackVue housing 20 can thus be moved using the TrackGlide unit 92in real-time, laterally, perpendicular to the direction of the runningrail 86, e.g. by the same magnitude as any detected lateral vehiclemotion but in opposite direction. This ensures that the TrackVuescanning sensors are at all times in the same relative position to thetrack as required to keep substantially the same relative field of viewof the track. In other examples, the mounting structure 84 including themounting members 88 and/or panel 89 could be used but without theTrackGlide unit 92 so as to define a static support structure.

In other examples of the invention, a static support structure and/orhousing could be used for mounting the overall system to the railwayvehicle but the actuation unit/system could actuate the relevantsensors, e.g. as well as any associated lighting, relative thereto. Insuch embodiments, it may not be necessary to actuate the entire housingand so other internal components within the housing may remain fixed inplace, whilst the sensors are moved to correspond to the relative trackposition there-beneath. The actuation system may be mounted within theouter housing. A single actuator could actuate all of the imagingsensors or just some of the sensors, for example with a plurality ofactuators being used to move different sets of sensors eitherindependently or in unison.

Thus according to aspects of the invention, there is provided a staticor rigidly mounted housing, and the track scanning sensors are mountedto an acutable support within the housing. The sensors may move relativeto a window in the housing. The actuator and/or a suitable linear trackor runner may be mounted within the housing.

The RPU 30 processes either image or laser based data to determine theposition of the rail and commands the linear actuator to follow the railposition as the vehicle moves at high speed by giving it data on thedirection and amount of movement required.

It has been found that adjustments to the height of the system 10relative to the track can be used to implement different inspectionmodes, e.g. wherein the system can be lowered to provide close railinspection or raised to provide a wider view of the overall track andits other components. Raising/lowering of the sensors is preferablyperformed for the system as a whole by providing a suitable verticalactuation mechanism within the mounting system 84.

FIG. 3 shows an example of a passenger train 46, to which the TrackVuesystem 10 may be mounted using any of the mounting options describedherein. The TrackVue system 10 is typically mounted on the underside ofthe rolling stock, for example on or adjacent a bogie 106 or betweenspaced bogies 106 of the rolling stock.

The power delivered by the vehicle to TrackVue in its native state maynot be 24 VDC and therefore a power converter 110 (typically a DC to DCpower converter) as shown in FIG. 3 can be placed anywhere on thevehicle within a reasonable distance of the system, if required, andshould provide uninterrupted power at 24 VDC or a desired voltage levelvia power connector 66 (FIG. 1).

The output of vehicle speed sensor on board the train 46 is used by theTrackVue system 10 in a manner to be described below. In this example avehicle wheel tachometer 112 is used to correlate travel speed by therate of vehicle wheel rotation, although a laser Doppler velocimetrydevice could equally be used. The signal output is preferably a pulsesignal provided at a pulse frequency according to the speed ofrevolution of the vehicle wheel. Typically multiple pulses are providedper wheel revolution. Other suitable vehicle speed indicators could beused provided they provide precise and substantially instantaneousoutput at a resolution suitable for use as a trigger signal for thetrack scanning sensors.

The vehicle 46 may comprise a location determination system, e.g.combined with inertial measurement system 54, which may communicate acurrent location with the TrackVue system 10, e.g. in addition to orinstead of the location determining system within housing 20. Thevehicle location determination system could comprise a conventionaltwo-dimensional location system, e.g. a GPS system or the like fordetermining latitude and longitude. In other examples, the locationdetermination system could determine location as a measure of distancealong the track from one or more known track locations. The locationdetermination system could comprise a vehicle travel distance sensor,such as the tachometer 112, and/or a track position sensor. This may beused in addition to, or instead of, a GPS location system. Combiningmultiple location determination systems/sensor types may be used toincrease the accuracy of asset location determination. The data from thetachometer and GPS may be combined to determine track curvature.

The use of a system for determining the distance of travel from a fixed,datum point on the track (i.e. a track position sensor) may bebeneficial in pinpointing the location of surveyed track features. Atrack position sensor may comprise a sensor for identifying trackfeatures indicative of known/predetermined track locations, e.g. fixeddatum locations. A scanning sensor 12, 24 (FIG. 1) of the kind describedabove could be used for this purpose or else a near-field wirelesscommunication transmitter/receiver 114 could be employed as shown inFIG. 3. An RFID scanner mounted on the train or as part of the commonlymounted system 10 could be used to detect RFID tags mounted on the trackat known locations. A lookup table of known tag locations may be used todetermine asset and/or image sensor location.

The operation of the TrackVue system in performing a track survey isdescribed below. The sealed nature of the housing 20 and the dedicatedlight sources 22 (FIG. 1) allow the TrackVue system to be used for railinspection at any time of day/night and in varying weather conditions.

The RPU 30 allows two forms of data processing. Firstly, real-time dataanalysis which uses a combination of either high speed processor 74coupled with FPGA 76 and/or graphics card 78 to process image/pixel dataand/or numerical/point data generated by the laser imaging device. Insuch analysis, logged imaging results are instant and there is nogrowing queue of data to process in a buffer. The FPGA and processor areselected to handle the expected volume and speed of incoming data (e.g.without requiring use of a buffer). Secondly, near real-time dataanalysis is possible using a library of software for high speedprocessor 74 and/or graphics card 78. Under these circumstances, theanalysis is quick but may not be real-time and a buffer of unprocessedsensor data may build up over time depending on the type of analysisbeing undertaken. Near real-time analysis can be continued after alldata acquisition has finished by either keeping the RPU 30 attached tothe main TrackVue body 20 on the vehicle 46, or by detaching it andlater attaching it to its docking station at a separate location, e.g.back office, as will be described below. Additionally, the dataconnections of the RPU 30 or housing 20 could be used to offload loggedimage data in a format suitable for subsequent processing.

The linescan sensor captures a line on the track at a desired resolutionand the TrackVue system builds up an image of the track or a sectionthereof by concatenating the lines together. The imaging resolution inpixel per millimetre in the direction of travel is a pre-set value, forexample 0.5 mm per pixel, which may be user specified/altered asrequired. For an imaging sensor to achieve this, it must be fast enoughto accommodate the relevant train speed. The imaging resolution in thedirection perpendicular to the direction of travel is based on the lensfield of view. For example, if an image width is 1000 mm and 2048 pixelsrepresent it, it equates to 0.48 pixels/mm.

The entire track image data can be constructed as a single image fromthe linescan output. However it is typical to divide the aggregatedimage data into smaller images, e.g. with the size of each divisionbeing decided based on a predetermined number of line scans, distancecovered and/or image file size. In this example, a line scan count ismaintained and a single image is defined every 2048 or 4096 line scans.The width of the image in pixels is determined by the imaging sensorcapability and may be in excess of 1000 pixels, such as typically 2048pixels or 4096 pixels, although different resolutions may be used fordifferent requirements.

The laser sensors generate rail profiles. In order to recover thecomplete rail profile, multiple laser sensors may be positioned suchthat the top, bottom and side of the rail may be profiled and furthercombined to generate an overall profile. A laser data profile consistsof multiple depth measurements and shows the relative differences inheight across measurements over the width of the rail. Rail geometry andprofiling (including relative measurements of the left-hand andright-hand rails) has been found to be highly dependent on the positionof the sensor relative to the rail. On a moving vehicle, the position ofthe laser sensor is not uniformly fixed. A number of factors includingvibration, shock, vehicle accelerations, bogie and railcar movements inthree dimensions, and rigidity of the sensors with respect tosurrounding framework all affect the dynamic pitch and roll of laser andother imaging sensors. In order to make meaningful/accurate rail ortrack geometry measurements, the effect of these various movements iscancelled out from the laser data profile. The commonly corrected datacan generate measurements that are accurate even when performing fullyautomated inspection. In contrast, it has been found that the comparisonof uncorrected sensor data can lead to false positives or actual defectsbeing overlooked. Furthermore, once uncorrected data has been recordedit is extremely difficult to retrospectively attempt to correlate datafrom one sensor that was misaligned with respect to another sensor.Correcting/correlating sensor data at the point of recordal based on acommon clock and inertia sensor measurement has been found to provide ahighly effective solution.

The ability of the inertial sensors to make accurate and concurrentmeasurements of relative movements between the laser/imaging sensors andthe inspected trach/assets has been found to be highly significant inmaking correct rail profile and track geometry measurements. In thisinvention, each laser sensor is tightly physically coupled with aninertial sensor. The vibration and dynamic accelerations experienced bythe laser sensor are therefore perfectly recorded by the inertialsensors and the data from these is used in real-time for laser datacorrection. The laser profile data is corrected in x, y and z dimensionsusing the inertial data before further measurements are extracted.

In examples where a Trackglide unit is provided for the actuation of thesensors, the inertia and laser/imaging sensors are commonly mounted foractuation at the same time.

FIG. 12 shows the TrackVue unit above the track. Internally, the laser24 and camera imaging sensors 12 are mounted on a linear actuator 96which is attached to a common support framework 98. This allows for bothtypes of imaging sensors to move on the linear actuator 96 such thatthey are always at the same relative position laterally with respect tothe rail.

The imaging sensors 12 and 24 responsible for one side of the rail arephysically mounted on a common rigid support member, such as a beam orplate 242 such that the relative motion between them can be minimised.An inertial sensor 54 is mounted on this same rigid support member suchthat it experiences the same dynamic forces as experienced by theimaging sensors. A common clock and triggering mechanism 241 is used totrigger and synchronise the measurements from various sensors, and timestamp them at a high resolution. The use of a synchronised triggeringmechanism with time indexing of measurements using a common clock hasbeen found to significantly benefit the performance of the system.

For any, any combination or all of the above sensor types, the frequencyof image (line, area or volume) capture may be controlled so as to beconstant with respect to the distance travelled along the railroad. Thusthe frequency or resolution over a length of track may be fixed. Inorder to achieve this, the frequency of image capture or scanning iscontrolled based on the vehicle speed. In the present examples, this isachieved by use of the vehicle wheel tachometer 112, as shown in FIG. 3,to provide a data capture regulation input, although in other examples asimilar control scheme could be implemented using any other conventionalvehicle speed sensor or odometer.

For a predetermined distance of travel, e.g. as sensed by apredetermined number or fraction of wheel revolution on the tachometer,a pulse signal is output to the relevant image capture device toinitiate an instance of image capture, e.g. as a frame/area, line orregion scan. Therefore, if the train accelerates, the relevant sensor(s)will scan more quickly, and if the train decelerates, the scanning rateis lowered accordingly. The operation of multiple imaging sensors,including digital cameras and/or laser sensors, can be synchronised suchthat they each trigger their data sampling at the same time. The rawdata for different sensors at a common time/location can thus becross-referenced within the indexed data store record.

The wheel tachometer 112 (FIG. 3) provides a fixed number of pulsesignals to the TrackVue connector/interface 64 (FIG. 1) for every wheelrotation thereby providing data on overall distance travelled, and speedof wheel rotation. The number of pulse signals is specified in terms ofa fixed value per rotation. The wheel tachometer 112 pulse output rateis selected to work for a given maximum vehicle speed at a desired levelof image resolution, e.g. such that the maximum scan rate is within theupper limit of the scanning sensors 12. TrackVue architecture isindependent of the choice of the tachometer or speed sensor and canreceive any suitable pulsed or other frequency control signal atinterface 64. For example, both wheel tachos fixed to the wheel orportable versions using laser Doppler can work as they provide a triggerin a suitable format, such as transistor-transistor logic or low voltagedifferential signalling format.

FIG. 5 details the overall data flow process (including the flow ofcontrol signals and track inspection data outputs) from sensor 12, 24outputs to the alerts/reporting tools for the end-user being displayedon an end user device 44 (FIG. 3), including the scan/image dataprocessing stages to analyse track components. Like reference numeralsare used to depict like features described above in relation to FIGS.1-3. Any, any combination, or all of the process stages may be automatedin accordance with examples of the invention. The use of modularsoftware 79 (FIG. 1) and/or hardware 72-78 allows the data processing tobe segmented into a plurality of tasks or ‘levels’, having the benefitthat one or more level can be prioritised or handled separately from oneor more further level.

The image 12 and/or laser 24 sensors record data which is passed on tothe main scan data processor 74 on-board TrackVue, comprising one ormore high speed processor. The sensor data output may connect directlyto the main processor 74 if no image compression is desired. Ifreal-time compression is desired, e.g. to JPEG format, the data flowsfrom imaging sensors to one or more FPGA or image grabbers, 76 whichcompress and reduce the quantity of data whist retaining the maximumpossible image quality for further examination. In certain cases, thecamera may itself compress the image data. The FPGA 76 also serves asthe hardware used for real-time scan data analysis and would worktogether with the main processor 74 to load appropriate image analysissoftware 79 for analysing scan data. The number of input connections onan FPGA 76 may be limited and therefore if several imaging sensors needto be connected then more than one FPGA board may be employed.

The main image processor 74 can also use an array of graphics cards 78to process image data using real-time or near real-time data analysis,or simply store it in memory for analysis at a later time. The raw datais passed from the sensors to system memory for storage in parallel tosending it for processing. The use of graphics cards allow the mainprocessor to spread the load of image analysis on multiple parallelcores significantly reducing the time to process image data. The datafor laser image acquisition is handled in exactly the same manner asimage data unless the laser device 24 (FIG. 1) has an internal dataprocessing capability, in which case data from it is directly passed tothe main processor 74 bypassing FPGA 76 and/or graphics card 78.

The overall system of processing uses multiple software modules. Themain processor 74 decides which software algorithm must be used forwhich sensor data from a pool of algorithms available within the datastore. The implementation of the software algorithms is different fordifferent hardware, for example, whether they need to be executed on agraphics card or FPGA. A software module or routine is a self-containedsoftware tool which can take an image frame (typically in data format asa matrix of numbers) or laser data (as a one, two or three dimensionalmatrix of numbers), and apply a series of arithmetic operations toprocess either the contents the incoming data represents, or to makemeasurements within such data.

A first software tool is for image and laser sensor data acquisition andcontrols the process of acquiring data including data flow from sensors,compression, sending it for analysis, recording it with a location (andoptionally a timestamp) and storage on the physical hard disk 80 as ascan database 80B.

All raw data needs to be stored to a physical memory 80A in addition topresenting it for analysis to appropriate processing hardware. For highspeed data acquisition, storing JPEG images in real-time may be timeconsuming and therefore pixel data will be stored in a flat filestructure which can be converted later into JPEG data by adding headerinformation to it. Laser scan data in compressed format are also storedin the non-volatile data store 80. The location for storage in terms ofdata directory can be specified by the system operator. The systemmaintains a database record 80B in the data store 80 that stores foreach raw data image collected, its location including GPS latitude andlongitude coordinates and/or a railroad line reference position. Incases where RFID location data is available, this will be stored inaddition to, or instead of, other location data.

A second software tool is for image and laser sensor data analysis andis responsible for executing a number of processing routines/algorithmson the collected data in either real or near real-time. If on-board dataanalysis option is not chosen, no data analysis is performed while datais collected. All data analysis in such cases is performed offline in aback office environment. For such cases, an FPGA can be replaced with asimpler frame grabber board which can only acquire data but cannotprocess it.

As the first stage of data analysis identifies the contents of interestwithin an image, e.g. identifying one or more data features that may beindicative of its contents. In case of two dimensional images, a matrixof numbers representing an image record for each position/pixel withinthe image, either a single value denoting the brightness of that pixel,or three numbers representing the red, green and blue channel colorvalues for that pixel.

One or more arithmetic operation is used to cluster pixels of similarproperties that are adjacent to each other, e.g. according to an imagesegmentation process. The image is thus broken down into a series ofclusters by assigning pixels to clusters according to brightness/colourand proximity to other pixels of the same/similar properties. For eachidentified cluster, a series of further operations are applied thatdetermine one or more property for the cluster, thereby defining afeature of the cluster that may be indicative of a corresponding featureof an asset captured in the image. The cluster properties assessed atthis stage may comprise any or any combination of a cluster edge,colour, texture, shape, pixel intensity and/or one or more otherstatistical property.

A general assumption is made that all pixels clustered togetherrepresent the same object/component given their visual similarity. Theprocess keeps track of which pixels (intensity value and coordinatepositions within the image) belong to which cluster. A pixel can onlybelong to one cluster at a given time.

The identified properties of each cluster can be used by a classifier(e.g. a software tool that classifies or recognises the identity ofobjects in image data based on what it has been trained to recognise).Thus classification of each pixel cluster is used to classify the trackcomponents represented by the clusters. Feature analysis and trackcomponent classification can be performed by separate modules.

In the analysis process, a range of artificial intelligence algorithmsthat build upon statistics and machine learning principles, coupled withsemantic knowledge of track layout that defines the probability ofassets in different parts of the image, are used. The integration ofsemantic knowledge or domain knowledge about track layout helps softwareautomatically eliminate false detections in analysis, and provides abetter recognition rate on objects of interest (track components ordefects).

The classification process/module matches the properties of each clusterto those of known objects (e.g. rail or sleeper). This process is knownas feature based matching. In some cases, an image template of the knownobject may be matched or correlated against the cluster of pixelsdirectly. This process is known as template matching. With either formof matching (feature or template based), if the level of match isgreater than a pre-set threshold, the cluster is labelled to be the sameas the object matched.

Unmatched clusters are assigned to be a part of the background.

The number of properties/features matched depends on the complexity ofknown objects, and has a direct bearing on the complexity of theanalysis algorithms and time taken to match. Once a scanned trackcomponent/object is labelled, the system stores a database record 80B inthe data store 80 comprising any, or any combination of: the imagesequence number where the object was found; a time stamp and/or locationrecord of where the object was imaged on the track; an object label;object properties within the image (e.g. any or any combination ofinformation on its centroid coordinates within the image, dimensionshorizontal and vertical, coordinates of points of interest or boundarypixels, colour, edge and/or texture and/or shape data), position of theobject relative to track centreline or running rail (field side or gaugeside) and its depth profile. Further information may be stored aboutwhether the detected asset has any defects or not, the nature of thosedefects, corresponding measurements and an indication of whether theyare surface or subsurface.

Based on the degree of match achieved with a known track component, thesystem allows logging of a confidence score or rating in the relevantdatabase in the data store 80, e.g. at 80B. A numerical assessment ofthe similarity between the imaged component and the predeterminedcomponent features or template feeds into a confidence score representedas a value on a defined scale, e.g. between 0 and 100, whereby 0represents no confidence and 100 represents highest possible confidence.The confidence estimate is directly based on the level of matchdetermined between the properties of a pixel cluster in the image, andof those of known objects, and takes into account the visibility of theobject (e.g. excess ballast estimates around recognised objects providea measure of visibility of objects).

The image analysis process follows a hierarchical approach. First, keyreference assets are recognised (see FIGS. 6 and 7) including rail top201, rail side 202, rail foot 203, ballast 204, sleeper 205, slab track206, plates 232, switch 217 and third/electrified rail 41.

A second stage processes pixel data from a smaller image area ofinterest comprising the image area covered by reference objectsidentified in the first stage and their surrounds. This is aimed atfurther identifying smaller objects of interest (e.g. spikes, orfasteners) which are then labelled as before.

In the third stage each reference object and the further objects arethereafter analysed for defects. The condition/defect analysis maycomprise one or a plurality of dedicated software modules. In general,the tool will compare the amassed image data for the identified objectagainst a predetermined (i.e. a nominal or previously recorded) objectmodel. The precise details of the model and/or the comparison undertakenwill typically differ between different track component types. Incertain respects, this may be similar to the feature/template matchingprocess described above, except that now that the component type isknown, the differences between the imaged object and the predeterminedmodel can be extracted and/or quantified to provide an account of thetrack component status.

A comparison may be made between geometric attributes of thepredetermined and scanned components, for example such as the componentorientation, e.g. angular orientation or relative position, or one ormore component dimension. Comparison may be made additionally oralternatively between surface properties (texture, colour) of thepredetermined and measured components, e.g. includingcontinuity/discontinuity of the surface.

The geometric and/or surface condition of an object can be analysedaccording to the present invention for detecting: (a) Wear and tear ofthe component; (b) Broken components; (c) Change in orientation of acomponent or part thereof, indicating damage; (d) Missing components ifprior information is available on what components are expected on agiven portion of track; and (e) Components obstructed from view becauseof snow, mud, leaves or sand thereon. Imaging sensors can evaluatecomponent condition based on its visual appearance, change in colour,presence of edges which can represent cracks, change in object boundaryorientation and so on. It is additionally or alternatively possible forinspection systems according to the invention to identify branding orproduct identification features in the surface of a track component.Thus the system may be able to assess make, age and/or product ID ofcomponents automatically. The system may recognise this information byeither performing optical character recognition on component surfacewriting or by detecting unique landmarks that provide metadata relatedto the component.

At a basic level, the system can report on the presence or absence of acomponent defect. Once detected, it is also possible to determinefurther characteristics for known of identifiable defect types, such as:defect classification (type of defect, name); defect severity (a gradevalue); defect properties (size, shape, colour, orientation and so on);and/or defect change (measurements showing change in properties overtime). A simple example may be a crack, the length and width of whichmay be tracked over repeated scans as the crack propagates over time.Similar techniques may apply to the dislodging or warping of componentsover time but may equally apply to instantaneous defects that can becompared to previous scan results or known defect types.

With reference to FIGS. 6 and 7, identifiable defects can be eithercaused by poor rail wheel interaction (rail wear 221, squats andwheelburns 223, switch defects 218, running band deviation 222),excessive stress on track components causing fracture or components tobreak away (gauge corner cracking 220, cracks on rail 224, cracks onfishplate 225, breaks 233 and cracks 235 on sleepers 205, abnormal railjoint gaps 207, missing bolts on fishplates 211, missing fasteners 212,rail discontinuity/break 219, missing spikes 227, raised spikes 228,missing anchors 230, base plate 232 movement either laterally orvertically, defects on electrified rail 41 b), temperature variations(abnormal expansion join gaps 208), and movement of the position ofrunning rail or electrified rail 41 (electrified rail position withreference to running rail measurements 41 a). The defect sizes andseverity data is stored in memory 80. The memory 80 also storesinformation on rail track assets (image objects) and defects(abnormalities within image objects) within a suitable cross-referencingdatabase structure. For example, as shown in FIG. 5 separate entries aremade for the analytical results at 80B and the sensor data storageitself at 80A. This can be achieved using separate tables within acommon database or separate, cross-referenced databases to storelocation of image data on disk, identified assets and defects with theirproperties, and time and location information.

A set of domain specific rules may applied on defect recognitions torule out false positives. This can be applied as a post-process on thedatabase table of defects 80B, or the scan analysis software 79 canapply this knowledge when identifying assets as part of the processdescribed above.

Where digital imaging sensors are used, the identity of certain trackcomponents or defects can be confirmed through their identification withlaser scan analysis of the track bed. Laser scan data analysis may alsobe used independently to identify track components, features and/ordefects, e.g. for components that are not readily perceivable usingdigital images or when a digital camera is unavailable. Laser scansprovide valuable depth information which can represent certain defectson components. A sudden change in depth profile of one component may benormal for some, and abnormal in other cases. For example, a change indepth profile of ballast/sleepers may be fairly normal, whereas, onedoes not expect the same on a railhead where it should be flagged as adefect.

First, locations/points of curvature change in laser scanned surfaceprofiles are measured which denote the edges of objects. The distancebetween two successive high curvature points is measured and evaluatedfor identity using a set of rules. For example, a raised segment withlength close to 80 mm represents the railhead provided another suchsegment can be identified at further a distance equal to the gauge ofthe track. Thus in different aspects of the invention, whether usinglaser or camera imaging, proximity/distance between assets or trackfeatures can be used to classify the track components as being of apredetermined type. The evaluation of depth based surface profilesallows the detection and recognition of assets, and their threedimensional measurements or that of their defects. Additional inertialdata is integrated into the analysis to provide a more accuraterepresentation of track objects in three dimensional space from whichdata, various track geometry features such as track gauge, twist andsuper-elevation can be measured.

FIG. 11 shows the core track geometry measurements that are made. Thedistance between rail (Gauge), elevation of one rail above the other(Cant) and any rail twists (Twist) can be measured. All of thesemeasurements require cross-referencing of data and measurements acrossthe plurality of laser sensors and correction of the sensor measurementsto account for dynamic forces before any final results are calculated.The data from the sensors also makes a number of secondary measurementsin real-time or post-processing including vertical profile (short andlong wave), horizontal profile (short and long wave), cant deficiency,and curvature (assisted with a high quality GPS device). The laserprofile data is also used to make rail wear measurements including thetop and side wear (volume, and wear depth).

The use of a common triggering mechanism and master clock for timestamping of data (241 in FIG. 12) is important in ensuring that thelaser profiles from multiple sensors are taken at precisely the sametime.

Further given that these are mounted on a rigid plate 242 and commonsupport structure 98 (FIG. 12), the rail profiles combined from them isof the same spot on the track with zero longitudinal displacement. Inshort, a common support structure combined with a synchronisedtriggering and master clock is used to facilitate the operation of thesystem with high accuracy in the dynamic environment during travel ofthe railroad vehicle. Existing systems lack a common support structurethat allows all vision sensors to keep the same relative positions withrespect to each other and with respect to the rail when the vehicle ismoving. Any spacing or relative movement between the inertia sensor andthe laser/imaging sensors can cause erroneous track geometrymeasurements with improper correction for vehicle dynamics. It has beenfound that the correlation and synchronisation of sensor signals nowproposed is not possible using conventional inspection train systems.

A combination of common support structure holding the Trackglideactuator unit which in turn holds all vision sensors on a rigid plate,and holds inertial sensors on the same rigid plate or attached to visionsensors, combined with synchronised triggering and time indexing with amaster clock makes the current equipment significantly more precise inits track geometry and profile measurements than existing solutions.

Laser and image analysis processes share several common components. Eachsystem's sampling rate can be controlled by vehicle speed using datafrom a shared wheel encoder 112 (FIG. 3). The control unit 42 (FIG. 1)ensures that the correct trigger and appropriate power is delivered toboth imaging and laser components for operation. These systems alsoreceive time and location information provided by the same external timesensors and location sensors. The level of sharing of data acquisitionand processing devices such as FPGA, graphics cards, processor, diskmemory and others depends on a chosen design and construction of theTrackVue system 10.

For several applications, such as tunnel inspection, a 360 degrees lasersweep profiling or three dimensional LIDAR imaging sensor may be used.This sensor 245 shown in FIG. 13 will be tightly coupled on the commonsupport structure with other imaging sensors and use the inertial datafor correction, in the manner hereinbefore described. FIG. 13 shows alaser sweep generating data points A, B, C and D as the laser sweepsinside a tunnel 242 for making measurements. A similar sweep may betaken outdoors for vegetation profiling, asset detection, and riskevaluation on a rail track. The sensor 245 will experience a range ofdynamic forces during the vehicle movement and unless the data iscorrected for these, it cannot be used for tunnel profiling that seeksto establish the clearance of the vehicle with respect to the tunnel. Inour invention the LIDAR and inertial sensors are mounted on the samecommon support structure to ensure that the data from inertial sensorsis relevant for making corrections. Furthermore, the master clock andsynchronised triggering system is used to drive all sensors includingLIDAR that generate data that can be easily cross-referenced. Forexample a camera based imaging sensor can evaluate a crack in the tunnelwall 244, or water seepage 243 and correlate this with clearancemeasurements provided by the LIDAR sensor 245. The high resolution ofinertial data and master clock allows each point in the laser pointcloud to be uniquely indexed for time and spatial position along withthe three-dimensional position of sensor 245 at the time of recordingthese measurements so that appropriate correction can be performed.

The modular architecture of software for image and laser dataacquisition and analysis provides possibilities of further interaction.In one scenario, it is possible for linescan and laser data analysis tobe completely independent. In another scenario, linescan data analysisinformation can be used to trigger a laser measurement or vice-versa. Inanother scenario, the data analytics from the laser and linescan data(from visible or nonvisible spectrum) may be combined together forgenerating a better understanding of asset and its condition. Forexample, the detection of plates 214 (FIG. 6) in linescan imagery maydetect a plate, which thereafter can trigger laser based measurement ofplate 232 movement (e.g. laterally and/or vertically). In another usescenario, laser and linescan measurements can be correlated so that oneset of measurements confirms or discredits the presence of an object(e.g. a fastener 212 or plate 214 in FIG. 6). Additionally oralternatively, the laser and linescan analysis can be cross referencedto provide additional context/meaning to laser measurements. Linescananalysis can provide details of object identity that lies under aprojected laser beam such that measurements can be labelled and makesense.

One or more laser data processing software module forms a part of theoverall image analysis software 79 (FIG. 1) and is responsible forobject recognition and measurement. TrackVue 10 uses laser technology tomake a number of such detections by evaluating the size, orientation andcurvature of a laser beam pattern (line, spots or grid) within a 2Dgrayscale image. With reference to examples in FIG. 6, this techniquecan be used to determine (a) rail wear 221 on rail top 201 and rail side202; (b) missing bolts on fishplates 211; (c) missing fasteners 212; (d)welds on rail foot 213; (e) plate depth movement 232 over the sleeper205; (f) depth of railhead defects such as tamped joints 207, squats andwheelburns 223; (g) switch defects 218 (FIG. 7); (h) the position ofrunning rail with reference to the position of electrified rail 41 a;(i) measure gaps in electrified rail and abnormalities 41 b; (j)unacceptable wear of electrified rail 41 b.

Using the techniques described above, a significant variety of trackcomponents, sub-components and defects can be identified and assessed,including, in addition to the features described above: rail grind marks237, welds 213, weld clamps 226, excess ballast 236, signalling assets238, magnets 239, cables 240, wheelcut 234, present or missing fastenerssuch as spikes 215, and anchors 216. For any track components orsub-components for which a predetermined spacing or orientation isexpected relative to one or more further components, the processingsteps described herein may be used to determine an amount of skew,misalignment or deformation for the measured component.

FIG. 10 shows the position of laser line patterns on rail, plate andsurrounding areas to make depth measurements as an illustrative exampleof how the laser beam pattern (a line in this case) can be projectedacross running rail features/components shown in FIG. 6. The relativedifferences in orientation of the beam in sections B (over a sleeper105) and C (over a plate 232) can provide details on vertical platemovement. Changes in beam straightness in section D (over rail foot 103)can provide data on the presence of fasteners 212 and welds 213. Thecorresponding curvature of beam between sections D (rail foot 103) and E(rail head 101) can provide data on rail wear 221. Beam straightness insection F (sleeper 105) can provide data on whether the beam is on asleeper 205 (e.g. a smooth surface) or ballasted area 204 (e.g. anirregular surface). The orientation of laser beam projected axiallyalong a rail itself shown as section GH can be used to determine therail slope and identify defects such as dipped or spaced rail sectionjoints 207.

An optional laser beam A projected onto the railway vehicle wheel canprovide further information for the measurement of the distance betweenthe wheel flange and the edge of the rail. This can provide additionalor alternative analysis of rail wheel interaction.

The scans generated by the laser unit can be analysed using one or twodimensional data analysis, or by first building a three dimensionalsurface and then applying three dimensional data analysis algorithms fordetermining the geometry of components, and further estimating theiridentity based on dimension and shape measurements from such profiles.The profiles are subject to noise and without information typicallyassociated with imaging sensors such as color and/or brightness/texture,the component recognition software for analysing laser data aloneachieves limited success. The asset identification and status assessmentalgorithms have been found to achieve better accuracy on assetrecognition by combining laser sensor data analysis with imaging sensordata analysis wherever possible.

Thermal imaging sensors can also be used to identify and/or detectdefects in track-related assets or components. Thermal images may beattained using digital images in the thermal/infra-red or near infra-redband of the electromagnetic spectrum. Taking of thermal images may betriggered in any of the ways described above for visual images and/orlaser scans. The processing of thermal images may be less rigorous andmay be used simply to identify the presence or absence of a heat source,e.g. as an elevated temperature region above ambient. Additionally oralternatively, thermal images may be processed in a manner akin tovisual pixel image data in order to identify pixel clusters andassociated features of components. Thermal images may be usedindependently to assess the presence/status of a component or inconjunction with the camera and/or laser scan data to improve thecertainty with which components can be analysed. In one example, theabsence of an expected heat signature may be used to indicate a defect,such as a broken cable or connection, which may or may not beidentifiable in other scan data sources.

X-ray and terahertz imaging allow the detection of internal flaws withincertain track components. X-rays can be used to detect internal railflaws whereas terahertz imaging can be used to detect internal sleeper(tie) flaws. Rail based flaws may comprise of internal cracks or airgaps, whereas sleeper based flaws may comprise of internal rot, airgaps, excess water and breaks. The images would be analysed with assetstatus analyser to determine internal condition of rails and sleepers(ties) as well as other components within the sensor field of view.

Using the above techniques for component classification, the system mayalso serve as a novelty/anomaly detector. In the event that foreignbodies are detected using the available sensor data that do not matchany predetermined asset models/types (e.g. that do not meet minimumthreshold confidence levels), or that were not present in previoussurveys, the relevant processor 72-78 and/or software module 79 of FIG.1 can output a finding of an unclassified object. The visual imagesand/or laser scan data in which the anomaly is present may be logged andan alert output identifying the presence of an anomaly, e.g. includingits location. Manual input may be required to identify the asset type,if necessary to update the record after inspection.

In any of the examples described above, it will be appreciated that thedata store 80 may comprise a database of known track component types,e.g. comprising a collection of pertinent component surface/colorfeatures, ranges of geometric values, edge features and/or otherfeatures such as temperature or surface texture. The captured scan datacan thus be compared to any such predetermined features or associatednumerical values when identifying components. The collection ofpredetermined feature values for known components may thus represent acomputational model of a component type.

Whilst the above system is described in terms of on-board processingsteps, the real-time image data logging allows subsequent analysis ofthe captured data for track asset recognition and status assessment.FIG. 4 shows a user console or system by which imaging data stored bythe RPU 30 can be analysed at a later time (offline processing) afterdata capture. In parallel with the defect and system status databecoming visible to the on-board operator, it may also be transmitted bythe cellular router 84 to a remote destination through which it isaccessible using a web-portal. In this manner, the remote end-user isable to review data analysis in near or close to real time. For furtheroffline post-processing, if required as an option, the RPU 30 can bedetached and used within a back office environment. It requires adocking station 116 within such an environment to receive power forcontinuing data analysis operations.

The docking station 116 takes power from a mains supply via a suitablepower connector 118 and converts it to power that can be used by the RPU30 by using a suitable power converter. Correct docking is assistedthrough the use of guiding pins 120 which align into correspondingdocking formations 121 in the station 116 for a secure mechanical andelectrical connection. Other electromechanical connectors may be used.The power/data connectors 62 of the RPU 30 are received by correspondingconnectors 119 in the docking station 116. In order to keep the RPU andthe docking station 116 cool for extended periods of operation involvedin any offline data analysis or review, a cooling unit 122 in thedocking station 116 using either air/convention, conduction cooling orliquid cooling may be used. In order to use the data within the RPU forreview and reporting, or for downloading or uploading files, the dockingstation can be connected to a computer 124 which can access the RPUthrough it using a standard data connection, e.g. USB or Ethernet/RJ45connector 123. The RPU can be connected to a local network for remoteaccess through the relevant network connection. The docking station 116may also have a power converter 126 to convert a conventional mains ACsupply to a DC supply for powering the RPU 30.

In summary of the above description, TrackVue can offer a compact andintegrated solution to the detection and condition assessment of railtrack components using surface and/or sub-surface data analysis andtrack geometry measurements whereby all sensor and processing equipmentmay be packaged inside a singular rugged assembly. The solution isdesigned for easy attachment to a range of vehicles, especiallypassenger and inspection trains, and is significantly more compact thanconventional track surveying and inspection systems that use separatein-cabin and out-cabin equipment. TrackVue is designed for low powerconsumption, which is a critical enabler for use on passenger trains, byreducing the number of electrical components used, improving systemdesign, and by selecting low power yet high performance components. Theexternal dependencies for operation of TrackVue are significantlyreduced compared to existing inspection train systems and can usewireless communication with an operator console 44 (FIG. 3). The overalldesign therefore significantly reduces the cabling/installation burdenas all connections between the camera and laser equipment, processingequipment and data storage are internal to TrackVue enclosure.

Depending on the choice of sensors and computational hardware, thesystem can operate from low vehicle speeds of 1-5 miles per hour up tospeeds of high speed trains, e.g. 220 miles per hour. At any suchspeeds, analysis of the track and associated components can be performedat relatively small increments in the direction of travel, such as forexample at 10 cm or smaller.

TrackVue can work in both “attended” and “unattended” mode. In the“attended” mode, the operator starts track surveying and inspectionprocess by powering on the system through a console application whichallows them to change any settings if needed before the start,otherwise, default settings apply. As track is surveyed, any alerts arefed back to the operator on their console 44 (FIG. 3) through a desktopapplication which provides real-time display of images and/or statisticson surveyed track. For real-time image and laser data analysis, anyassets detected are presented to the operator and can be overlaid on amap or other on-screen visual track representation. In case of nearreal-time scan data analysis, a pool of image/laser data waiting to beprocessed is maintained and recorded in database. The position of thevehicle using one or more location sensors (e.g. GPS, line reference,RFID) can be displayed for all track components and/or data collected.One, two or three-dimensional plans of the surveyed route can begenerated using the surveying system described herein, in which thetrack and relative locations of identified components/defects aremarked.

At least one wireless or a wired connection is established between thesystem enclosure and the console 44 mounted inside the vehicle foroperator inspection and/or use. This can transmit in real-timeinformation on raw data, track components, their condition,measurements, and system status to the operator which can be displayedon the console 44.

A reporting tool allows for a range of asset survey reports and graphsto be generated. The format of reports and graphs is optimised for theend-user. Any problems associated with TrackVue performance ormalfunction is displayed for correction at the operator console. At theend of vehicle run, the console also displays the current status of dataanalysis. If real-time analysis is chosen, all analysis is finished atthe time of the end of the current run. In case of near real-timeanalysis, the console shows the amount of data waiting to be processed.At this stage, the operator has the option of continuing on with theanalysis, or to stop the analysis. Any unfinished analysis can becarried out the next time TrackVue is started or by removal of the RPUand attachment to a power source, e.g. such as a docking station withina back office environment for completing all remaining data analysis. Inthis case the RPU serves as a replacement for data analysis in a backoffice environment. Once the data analysis is complete, the results canbe offloaded from it through a USB connection by copying track imageryand results database, or by simply removing a detachable disk.

A separate offline desktop software can be used by end-users in anoffice environment to perform a number of tasks including: (i) Reviewingof detected track components and their condition using rail route mapsor other GIS maps where available, and applying tools for eliminatingany false detections; (ii) Generation of survey reports for maintenancedetailing track components and their condition; (iii) Comparison ofanalysis from multiple previous runs to see the changes in trackcondition; (iv) Generate a risk assessment report for identified trackcomponents; (v) Generate a labelled plan of the track; (vi) Generate areport detailing novel features on track, for example excess sand, mudor snow, or unusual objects; (vii) Print or export to portable devicesvarious defect data, reports and any other statistics; (ix) Planmaintenance for short or long term strategic planning on equipmentrepairs or replacement; (x) Plan for any track renewals; (xi) Exportinganalysis to a centralised Engineering Data Management System whichcontains a wider set of track condition information; (xii) Exportinganalysis to any web-portals or external databases; (xiii) Exportinganalysis to portable devices which can be used by track engineers towalk the track; (xiv) Comparison of automated data analysis reports withrelevant track maintenance or track walking records to audit theirquality; and (xv) Review imaging sensor data analysis integrated withlaser scan data. Any of said tasks may be performed by the on-boardTrackVue system as necessary in other implementations of the invention.

During use on-board a railroad vehicle, in an “unattended mode”, thesystem starts automatically on receiving power from the external source.Data acquisition sensors and lighting units are triggered to startoperation once data from the wheel tacho or other suitable signal inputconfirms that the vehicle is in motion. If the vehicle stops for aperiod greater than a pre-set threshold, the sensors stop recording. Thesystem does not require a console to display data acquisition or defectanalysis. Instead, the results are transmitted to the Train InformationManagement System (TIMS) directly, or through email/wirelesscommunication to an external Operation control Centre (OCC). Any furtheractions taken on such communication is the responsibility of TIMS orCCC. In case if a “near real-time” data analysis approach is employed onan unattended system, it is programmed to continue data processing aslong as mains power or battery power is available and buffer dataanalysis for future runs if needed.

The system can be used for a wide variety of tasks including trackcomponent recognition and registration, track condition monitoring,change and degradation detection, track risk evaluation, generating mapsof track with assets/defects embedded within such a map, detection ofnovel and threat objects, and measurement of track/rail properties suchas curvature. Thus the invention may allow plotting the analysis resultswith the available location data to produce Geographical InformationSystem (GIS) maps for print or export. By repeating the analysis atregular time intervals, changes in component conditions and theassociated level of risk can be determined.

The system can thus be used to generate risk reports on track sectionswhich will contain information on track defect identity, position,and/or risk severity. Reports containing information obtained throughuse of the invention may be output by the system and used for planningany or any combination of track checks, maintenance, repair/renewal,removal and/or replacement.

What is claimed is:
 1. A railroad track inspection system for mountingto a railroad vehicle, comprising: a plurality of track scanning sensorscomprising one or more visual imaging sensor and one or more lasersensor system for three dimensional track geometry measurement; aninertia sensor; a data store for storing track scan data recorded by thetrack scanning sensors; and a scan data processor for automatic analysisof said track scan data upon receipt thereof to detect one or more trackcomponents within the scan data; wherein the system comprises a commonhousing defining an enclosure for the track scanning sensors, theinertia sensor, and scan data processor, the common housing having acommon support structure on which the track scanning sensors and inertiasensor are mounted, the common housing having a mounting for attachmentof the system to a railroad vehicle in use; and wherein the scan dataprocessor is arranged to receive concurrent sensor signal outputs of theplurality of tack scanning sensors and the inertia sensor and to correctthe output of one or more of the track scanning sensors based on theoutput of the inertia sensor so as to account for dynamic forcesexperienced by said one or more track scanning sensor during motion ofthe railroad vehicle.
 2. The system according to claim 1, comprising amaster clock and a triggering unit for synchronising operation of theinertia sensor and the plurality of track scanning sensors to outputsensor data according to a common master clock signal.
 3. The systemaccording to claim 2, wherein the data store comprises correspondingtime indexed data entries for the inertia and track scanning sensors. 4.The system according to claim 2, wherein the triggering andsynchronisation of the inertia and imaging sensors and time stamping ofdata is managed according to the common master clock signal.
 5. Thesystem according to claim 1 wherein the scan data processor correlatesthe sensor data output from one or more visual imaging sensor and one ormore laser sensor system after the correction based on the output of theinertia sensor.
 6. The system according to claim 1, wherein the scandata output of the track scanning sensors that is corrected by said scandata processor comprises the three-dimensional track geometrymeasurement by the laser sensor system, and said corrected scan data isused by the scan data processor to detect one or more track componentswithin the scan data from a predetermined list of component typesaccording to one or more features identified in said corrected scandata.
 7. The system according to claim 6, wherein the scan dataprocessor performs template matching of the corrected scan data withpredetermined ideal rail profile data to identify differences that formthe basis of a track geometry and/or rail profile measurement output bythe system.
 8. The system according to claim 1, wherein the commonsupport structure comprises a unitary rigid member to which both theinertia sensor and one or more track scanning sensor are mounted suchthat said inertia sensor experiences the same dynamic forces as saidtrack scanning sensor in use.
 9. The system according to claim 1,wherein the common housing comprises a rigid enclosure within which thetrack scanning sensors, the inertia sensor, the data store and scan dataprocessor are housed as a single, standalone module, and wherein themounting is arranged for attachment to the exterior of the railwayvehicle.
 10. The system according to claim 1, wherein the scan dataprocessor and data store are provided in the common housing as aremovable processing unit, which is releasably mechanically andelectrically coupled to the common housing by one or more connectorformation.
 11. The system according to claim 10, wherein the removableprocessing unit comprises a sealed unit, an internal space of which isisolated from an interior of the common housing when connected thereto.12. The system according to claim 1, wherein the common housingcomprises a common power supply device for connecting the system to therailway vehicle and a battery arranged to power at least the scan dataprocessor and sensors such that storage and/or analysis of the trackscan data can be performed by the system for a period of absence ofexternal power to the system.
 13. The system according to claim 1,wherein the track scanning sensors are adjustably mounted on the commonsupport structure relative to the mounting and the system comprises anactuator and a controller for dynamically adjusting a field of view ofthe image capture sensors whilst the vehicle is in motion, wherein thecontroller is arranged to adjust the field of view of the sensorsautomatically based on the location or absence of one or more identifiedfeature or track component in the scan data relative to the field ofview.
 14. The system according to claim 1, wherein the visual imagingsensor is part of a visual imaging system comprising at least onedigital image capture sensor or camera and the laser sensor systemcaptures three-dimensional surface profile data of the one or more trackcomponents and the scan data processor automatically identifies featurescorresponding to the same one or more track components in both thethree-dimensional surface profile data and the images from the digitalimage capture sensor.
 15. The system according claim 1, wherein the scandata processor receives the output of the inertia sensor and the lasersensor system so as to determine a three-dimensional position of trackcomponents in space.
 16. The system according to claim 15, wherein thescan data processor uses the output of the laser sensor system to makemeasurements on rail wear, and track geometry measurements including anyor any combination of track superelevation, twist, curvature and gauge.17. The system according to claim 1, wherein one or more of the trackscanning sensors is arranged to perform subsurface imaging of trackcomponents for assessment of the internal structure of the railroadtrack by the scan data processor.
 18. The system according to claim 17,comprising an energy source for irradiating at least a portion of thetrack in a non-visible wavelength of electromagnetic spectrum, such thattransmission through the track and/or reflectance from the track can beimaged using one or more track scanning sensor to provide an image ofthe object's internal structure, wherein the non-visible electromagneticradiation may comprise terahertz or x-ray radiation.
 19. The systemaccording to claim 1, arranged to measure and record three dimensionalproperties of defects in rails and/or other track components includingdefect depth profile and/or maximum depth.
 20. The system according toclaim 1, wherein the system operates in an unattended mode and each ofstarting track scan data acquisition, stopping track scan dataacquisition, track scan data recordal and processing by the system isfully automated in response to one or more sensed operational parameterfor the railway vehicle, the one or more processor being arranged toperform analysis of the track scan data and the system furthercomprising a wireless transmitter to transmit automatically the resultsof said data processing from the vehicle to a remote operational controlcentre.
 21. The system according to claim 1, wherein the track scan dataprocessor is arranged to determine a track gauge value from the trackscan sensors under vehicle load conditions, the track gauge value beingcompared to a further track gauge measurement of unloaded track so as todetermine a difference in gauge between loaded and unloaded rail trackconditions, the processor outputting an indication of gauge strengthmeasurement.
 22. The system according to claim 1, wherein the scan dataprocessor determines geometry changes and/or wear in the track rails atan interval of 10 cm or smaller along the direction of travel over anormal range of vehicle travel speeds for conventional passenger orfreight rail vehicles.
 23. The system according to claim 1, wherein theenclosure comprises a plurality of window portions, each portion beingarranged in the field of view of one or more of said track scanningsensors, wherein at least one window portion is arranged at a differentangular orientation to at least one further window portion.
 24. Thesystem according to claim 1, further comprising a location determinationsystem, the scan data processor being arranged to index scan data with alocation determination record corresponding to the location at which thescan data was obtained.
 25. The system according to claim 24, whereinthe location determination system comprises a vehicle travel distancesensor for determining the location of said sensor relative to a fixeddatum point on the railroad track.
 26. The system according to claim 25,wherein the vehicle travel distance sensor output is correlated with alocation reading from a geographic coordinate determining system. 27.The system according to claim 1, wherein the scan data processor isarranged automatically to construct an image of a length of the railroadtrack from a plurality of consecutive scans from one or more of thetrack scanning sensors.
 28. The system according to claim 1, wherein thescan data comprises one or more matrix of pixel intensity and/or colorvalues and the scan data processor is arranged to identify features insaid scan data by clustering pixels according to said intensity and/orcolor values.
 29. The system according to claim 1, comprising: arailroad vehicle travel sensor for sensing the speed, direction and/ortravel distance of the railroad vehicle; and a controller arranged totrigger a scan by the track scanning sensors according to an output ofsaid vehicle travel sensor.
 30. The system according to claim 29,wherein the vehicle travel sensor provides a pulsed output, thefrequency of which corresponds to vehicle speed and a scan by the trackscanning sensors is triggered by each pulse or a predetermined number ofpulses.
 31. The system according to claim 1, wherein the scan dataprocessor determines a confidence score for a track componentdetermination according to a degree of a match between a plurality ofgeometric and/or surface property features of a track componentidentified in the track scan data and one or more predeterminedcomponent features.
 32. The system according to claim 1 adapted formounting to a passenger or freight revenue generating railway vehicle orlocomotives in use.
 33. The system according to claim 1, furthercomprising a thermal imaging sensor used for component conditionanalysis.
 34. The system according to claim 44, wherein the one or morevisual imaging sensor comprises a plurality of areascan and/or alinescan imaging sensors.
 35. The system according to claim 1, whereinthe scan data processor comprises a plurality of asset classifiers andan asset status analyser comprising two or more of a rule-basedclassifier, a template-based classifier and a statistical featurematching tool.
 36. The system according to claim 1, wherein the scandata processor identifies one or more pixel clusters within an imageaccording to one or more pixel brightness or colour property, each pixelclusters being used by the scan data processor to determine an edge,colour, texture and/or shape feature of a track asset.
 37. The systemaccording to claim 36, wherein the scan data processor determines achange in the asset edge, colour, texture and/or shape feature relativeto a previously determined corresponding asset feature.
 38. A railroadtrack inspection system for mounting to a railroad vehicle, comprising:a plurality of track scanning sensors comprising a laser sensor systemfor track surface profile measurement; an inertia sensor; a data storefor storing track scan data recorded by the track scanning sensors; ascan data processor for automatic analysis of said track scan data uponreceipt thereof to detect one or more track components within the scandata; wherein the system comprises a common housing defining anenclosure for the track scanning sensors, the inertia sensor, and scandata processor, the common housing having a mounting for attachment ofthe system to a railroad vehicle in use; and a master clock and atriggering unit for synchronising operation of the inertia sensor andthe plurality of track scanning sensors to output sensor data accordingto a common master clock signal; wherein the scan data processor isarranged to receive and process concurrent sensor signal outputs of theplurality of tack scanning sensors and the inertia sensor.
 39. Arailroad track inspection system for mounting to a railroad vehicle,comprising: a plurality of track scanning sensors comprising one or morevisual imaging sensor and one or more laser sensor system for threedimensional track geometry measurement; an inertia sensor; a data storefor storing track scan data recorded by the track scanning sensors; anda scan data processor for automatic analysis of said track scan dataupon receipt thereof to detect one or more track components within thescan data; wherein the system comprises a common housing defining anenclosure for the track scanning sensors, the inertia sensor, and scandata processor, the common housing having a common support structure onwhich the track scanning sensors and inertia sensor are mounted, whereinthe scan data processor is arranged to receive and process concurrentsensor signal outputs of the plurality of tack scanning sensors and theinertia sensor; and wherein the common housing having a mounting forattachment of the system to a railroad vehicle in use.
 40. A railroadtrack inspection method, comprising: providing a common supportstructure to which a plurality of track scanning sensors, a data storeand a scan data processor are attached, the common support structurehaving a mounting attached to a railway vehicle in use; operating theplurality of track scanning sensors comprising one or more visualimaging sensor and one or more track geometry measurement sensor systemfor three dimensional surface profile measurement; and storing trackscan data recorded by the track scanning sensors in the data store;wherein the scan data processor performs automatic analysis of saidtrack scan data upon receipt thereof to detect one or more trackcomponents within the scan data from a predetermined list of componenttypes according to one or more features identified in said scan data.